Add colon after work package subject in header.

frontend/app/templates/work_packages.show.html

@@ -1,7 +1,7 @@
 <div class="work-packages--show-view">
   <div class="toolbar-container">
     <div toolbar id="toolbar">
-      <h2 title="{{workPackage.props.subject}}"><a href="" ng-bind="type.props.name" /> {{workPackage.props.subject}}</h2>
+      <h2 title="{{workPackage.props.subject}}"><a href="" ng-bind="type.props.name" />: {{workPackage.props.subject}}</h2>
 
       <ul id="toolbar-items">
         <li class="toolbar-item">