Fixed issue in 'img-retina' mixin where 'file-1x' and 'file-2x' variables weren't being properly expanded due to enclosing quotes.
Bump version to 3.0.0.3
Merge branch 'hotfix/v3.0.0.3'

* hotfix/v3.0.0.3:
  Bump version to 3.0.0.3
  Fixed issue in 'img-retina' mixin where 'file-1x' and 'file-2x' variables weren't being properly expanded due to enclosing quotes.