Merge pull request #1195 from teojgo/enhancement/add_logo_readme

[doc] Add ReFrame logo to README

Author: Vasileios Karakasis

README.md

@@ -1,3 +1,7 @@
+<a href="http://github.com/eth-cscs/reframe">
+  <img src="docs/_static/img/reframe_logo-full.png" width=400>
+</a>
+
 [![Build Status](https://travis-ci.org/eth-cscs/reframe.svg?branch=master)](https://travis-ci.org/eth-cscs/reframe)
 [![Documentation Status](https://readthedocs.org/projects/reframe-hpc/badge/?version=latest)](https://reframe-hpc.readthedocs.io/en/latest/?badge=latest)
 [![codecov.io](https://codecov.io/gh/eth-cscs/reframe/branch/master/graph/badge.svg)](https://codecov.io/github/eth-cscs/reframe)<br/>
@@ -9,7 +13,7 @@
 [![Slack](https://reframe-slack.herokuapp.com/badge.svg)](https://reframe-slack.herokuapp.com/)<br/>
 [![License](https://img.shields.io/badge/License-BSD%203--Clause-blue.svg)](https://opensource.org/licenses/BSD-3-Clause)
 
-# ReFrame
+# ReFrame in a Nutshell
 
 ReFrame is a framework for writing regression tests for HPC systems.
 The goal of this framework is to abstract away the complexity of the interactions with the system, separating the logic of a regression test from the low-level details, which pertain to the system configuration and setup.