string comparisons

fix string comparisons within a template

eg.

```<div class="canvas-container" ng-class="{'canvas-expanded' :
!canvas.showInspector}">```

atm all single quotes get stripped which would turn the following into

```<div class="canvas-container" ng-class="{canvas-expanded :
!canvas.showInspector}">```

where angular will now try to find ‘canvas-expanded’ function instead
of a string