feat(bootstrap): Add bootstrap-compatible stylesheet

Add support for Bootstrap colors and transitions..
Merge PR #155
feat(tagsInput): Add support for some Bootstrap classes

Add support for the following Bootstrap classes:
- input-group
- input-group-lg
- input-group-sm
- input-lg (via ti-input-lg class)
- input-sm (via ti-input-sm class)
- has-feedback
- has-success
- has-error
- has-warning

Closes #78.
feat(configuration): Add setTextAutosizeThreshold method

Add a new method to the tagsInputConfig service to allow the threshold
used by the tagsInput directive to re-size the input element based on its
content to be configured.

Closes #181
chore(grunt): Add Boostrap files to the compress task
chore(README): Update Installing section [skip ci]
chore(grunt): Fix update-bower-version task
chore(packages.json): Add bugs and keywords properties
chore(grunt): Generate tarball for NPM
chore(release): Release v2.1.0
fix(tagsInput): Fix has-success, has-warning and has-error classes

Fix Bootstrap validation classes by removing their dependency on the
has-feedback class.
chore(grunt): Add build folder to NPM tarball
chore(release): Bump version to 2.1.1
chore(release): Release v2.1.1
chore(README): Fix header styling
docs(tagsInput): Fix type option documentation [skip ci]
docs(README): Fix link to the API documentation page
chore(package.json): Add main property