Add and update Badges (#159)

* travis -> circleci badge

* add other badges

Author: danvk

README.md

@@ -1,8 +1,22 @@
-[![Build Status](https://travis-ci.org/danvk/webdiff.svg?branch=master)](https://travis-ci.org/danvk/webdiff)
 # git webdiff
 
 Two-column web-based git difftool.
 
+<p align="center">
+  <a href="https://pypi.org/project/webdiff/" target="_blank">
+    <img alt="PyPI - Version" src="https://img.shields.io/pypi/v/webdiff">
+  </a>
+  <a href="https://dl.circleci.com/status-badge/redirect/gh/danvk/webdiff/tree/master" target="_blank">
+    <img alt="CircleCI 📝" src="https://dl.circleci.com/status-badge/img/gh/danvk/webdiff/tree/master.svg?style=svg">
+  </a>
+  <a href="https://github.com/danvk/webdiff/blob/master/LICENSE" target="_blank">
+    <img alt="License: Apache2 📝" src="https://img.shields.io/github/license/danvk/webdiff">
+  </a>
+  <a href="https://github.com/sponsors/danvk" target="_blank">
+    <img alt="Sponsor: On GitHub 💸" src="https://img.shields.io/badge/sponsor-on_github_💸-21bb42.svg" />
+  </a>
+</p>
+
 Features include:
 
 * Side-by-side (two column) diff view