preserve pip errors so travis reports install failures better
Merge branch 'travis-install-failure'
Remove view_instance from WidgyViewMixin.

This was left over from how we were doing permissions for the Review
Queue before.  It is not being used anywhere now.
sprites
Use a ::before pseudo-element for icons in shelf.

The ::before pseudo-element gives us more control over the exact output
dimensions and positioning of the icon.
Remove unused and duplicate widget icons.
html.admin.scss was missing widgy_common.
Use widgy_common.scss in django.fusionbox.scss
Merge pull request #230 from fusionbox/fix_scss_errors

Fix scss errors
need to ignore demo/static too
Merge pull request #227 from fusionbox/sprites4

Sprites for widget icons