Add more links/badges to README

 - Badges for download, homebrew, gitter, maintenance etc. and tweet
   button at top
 - Social links and tweet button at footer

Author: zbeekman

README.md

@@ -7,14 +7,16 @@
 OpenCoarrays
 ============
 
+[![Maintenance](https://img.shields.io/maintenance/yes/2017.svg?style=flat-square)](https://github.com/sourceryinstitute/opencoarrays/commits/master)
 [![CI Build Status][build img]](https://travis-ci.org/sourceryinstitute/opencoarrays)
+[![Gitter](https://img.shields.io/gitter/room/nwjs/nw.js.svg?style=flat-square)](https://gitter.im/sourceryinstitute/opencoarrays)
 [![GitHub license][license img]](./LICENSE)
+[![GitHub release][release img]](https://github.com/sourceryinstitute/opencoarrays/releases/latest)
+[![homebrew](https://img.shields.io/homebrew/v/opencoarrays.svg?style=flat-square)](http://braumeister.org/formula/opencoarrays)
 [![Download as PDF][pdf img]](http://md2pdf.herokuapp.com/sourceryinstitute/opencoarrays/blob/master/README.pdf)
-<!-- [![GitHub release][release img]](https://github.com/sourceryinstitute/opencoarrays/releases/latest) -->
+[![Twitter URL](https://img.shields.io/twitter/url/http/shields.io.svg?style=social)](https://twitter.com/intent/tweet?hashtags=HPC,Fortran,PGAS&related=zbeekman,gnutools,HPCwire,HPC_Guru,hpcprogrammer,SciNetHPC,DegenerateConic,jeffdotscience,travisci&text=Stop%20programming%20w%2F%20the%20%23MPI%20docs%20in%20your%20lap%2C%20try%20Coarray%20Fortran%20w%2F%20OpenCoarrays%20%26%20GFortran!&url=https%3A//github.com/sourceryinstitute/opencoarrays)
 <!-- [![Release Downloads][download img]](https://github.com/sourceryinstitute/opencoarrays/releases) -->
 
-Download this file as a PDF document [here](http://md2pdf.herokuapp.com/sourceryinstitute/opencoarrays/blob/master/README.pdf).
-
 * [Overview](#overview)
 * [Downloads](#downloads)
 * [Compatibility](#compatibility)
@@ -88,6 +90,14 @@ We gratefully acknowledge support from the following institutions:
 * The National Energy Research Scientific Computing Center ([NERSC]), which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, for access to the Hopper and Edison supercomputers under the OpenCoarrays project start allocation.
 * [Sourcery, Inc.], for financial support for the domain registration, web hosting, advanced development, and conference travel.
 
+---
+
+[![GitHub forks](https://img.shields.io/github/forks/sourceryinstitute/opencoarrays.svg?style=social&label=Fork)](https://github.com/sourceryinstitute/opencoarrays/fork)
+[![GitHub stars](https://img.shields.io/github/stars/sourceryinstitute/opencoarrays.svg?style=social&label=Star)](https://github.com/sourceryinstitute/opencoarrays)
+[![GitHub watchers](https://img.shields.io/github/watchers/sourceryinstitute/opencoarrays.svg?style=social&label=Watch)](https://github.com/sourceryinstitute/opencoarrays)
+[![Twitter URL](https://img.shields.io/twitter/url/http/shields.io.svg?style=social)](https://twitter.com/intent/tweet?hashtags=HPC,Fortran,PGAS&related=zbeekman,gnutools,HPCwire,HPC_Guru,hpcprogrammer,SciNetHPC,DegenerateConic,jeffdotscience,travisci&text=Stop%20programming%20w%2F%20the%20%23MPI%20docs%20in%20your%20lap%2C%20try%20Coarray%20Fortran%20w%2F%20OpenCoarrays%20%26%20GFortran!&url=https%3A//github.com/sourceryinstitute/opencoarrays)
+
+
 [Hyperlinks]:#
 
 [Overview]: #overview
@@ -131,6 +141,6 @@ We gratefully acknowledge support from the following institutions:
 [build img]: https://img.shields.io/travis-ci/sourceryinstitute/opencoarrays/master.svg?style=flat-square "View Travis-CI builds"
 [CI Master Branch]: https://travis-ci.org/sourceryinstitute/opencoarrays?branch=master "View Travis-CI builds"
 [download img]: https://img.shields.io/github/downloads/sourceryinstitute/opencoarrays/total.svg?style=flat-square "Download count image source"
-[license img]: https://img.shields.io/badge/License-BSD--3-blue.svg?style=flat-square "View BSD-3 License"
+[license img]: https://img.shields.io/badge/license-BSD--3-blue.svg?style=flat-square "View BSD-3 License"
 [release img]: https://img.shields.io/github/release/sourceryinstitute/opencoarrays.svg?style=flat-square "View latest release"
 [pdf img]: https://img.shields.io/badge/PDF-README.md-6C2DC7.svg?style=flat-square "Download as PDF"