Fix 404 error of theme file (due to AngularJS not being loaded yet).

This fixes a 404 error that happens when the application is first loaded and
the browser tries to fetch the file "/dist/{{getTheme()}}_style.css" without
interpolating the `getTheme()` function, since AngularJS is not loaded yet.
Merge pull request #197 from deborasetton/issue/theme-load-error

Fix 404 error of theme file (due to AngularJS not being loaded yet).