Add coveralls badge to doc site and README.md.

Testing Done:
Sample doc site publish here - you may need to refresh: http://pantsbuild.github.io/jsirois/index.html
And README.md renders as such: https://github.com/jsirois/pants/blob/d5e2a149c2fc368327524d8c7b16168a8936c5db/README.md

Bugs closed: 369, 544

Reviewed at https://rbcommons.com/s/twitter/r/972/

README.md

@@ -7,7 +7,8 @@ many distinct projects.
 Friendly documentation: http://pantsbuild.github.io/
 
 We use [Travis CI](https://travis-ci.org) to verify the build
-[![Build Status](https://travis-ci.org/pantsbuild/pants.svg?branch=master)](https://travis-ci.org/pantsbuild/pants/branches)
+[![Build Status](https://travis-ci.org/pantsbuild/pants.svg?branch=master)](https://travis-ci.org/pantsbuild/pants/branches).
 
-We use Coveralls for code coverage: [![Coverage Status](https://coveralls.io/repos/pantsbuild/pants/badge.png)](https://coveralls.io/r/pantsbuild/pants)
+We use [Coveralls](https://coveralls.io) to monitor test coverage
+[![Coverage Status](https://coveralls.io/repos/pantsbuild/pants/badge.png?branch=master)](https://coveralls.io/r/pantsbuild/pants).
 

src/python/pants/docs/_templates/layout.html

@@ -15,12 +15,22 @@
     ga('create', 'UA-39101739-2', 'auto');
     ga('send', 'pageview');
 
-    // Show the travis-ci status graphic
+    // Show the travis-ci status graphic.
     $('.wy-breadcrumbs').append(
-      '<div style="float: right;">' +
-      '<a href="https://travis-ci.org/pantsbuild/pants">' +
-      '<img src="https://travis-ci.org/pantsbuild/pants.png?branch=master">' +
-      '</a></div>');
+      '<div style="float: right; padding: 1px;">' +
+        '<a href="https://travis-ci.org/pantsbuild/pants">' +
+          '<img src="https://travis-ci.org/pantsbuild/pants.png?branch=master">' +
+        '</a>' +
+      '</div>');
+
+    // Show the coveralls status graphic.
+    $('.wy-breadcrumbs').append(
+      '<div style="float: right; padding: 1px;">' +
+        '<a href="https://coveralls.io/r/pantsbuild/pants?branch=master">' +
+          '<img src="https://coveralls.io/repos/pantsbuild/pants/badge.png?branch=master"' +
+          '     alt="Coverage Status">' +
+        '</a>' +
+      '</div>');
   });
 </script>
 <style type="text/css">