Refine Swift version filter buttons on evolution dashboard (#416)

Reduce visual clutter and enable a more compact interface by using only version number on buttons.

This removes 20 repeated occurances of 'Swift', one on each button.

Change 'Language Version' heading to 'Swift Version' preserving the clarity of the repeated usages of 'Swift'

Resolves #295

Author: dempseyatgithub

assets/javascripts/swift-evolution.js

@@ -295,7 +295,7 @@ function renderSearchBar () {
 
   if (implementedCheckboxIfPresent) {
     // Add an extra row of options to filter by language version
-    var versionRowHeader = html('h5', { id: 'version-options-label', className: 'hidden' }, 'Language Version')
+    var versionRowHeader = html('h5', { id: 'version-options-label', className: 'hidden' }, 'Swift Version')
     var versionRow = html('ul', { id: 'version-options', className: 'filter-list hidden' })
 
     var versionOptions = languageVersions.map(function (version) {
@@ -310,7 +310,7 @@ function renderSearchBar () {
           tabindex: '0',
           role: 'button',
           'for': 'filter-by-swift-' + _idSafeName(version)
-        }, 'Swift ' + version)
+        }, version)
       ])
     })