[Fix] Corrected gulp test task enforcing specific version of gulp-usemin node module

- "test" task and "test:e2e:settings" tasks modified to correctly run and also removed unnecessary tasks
- Specifying version 0.3.7 of gulp-usemin as latest updates of this module break our build
Merge pull request #13 from stulees/chore/settings-html

[Fix] Corrected gulp test task enforcing version of gulp-usemin module