Update Bootstrap CSS source and relevant tests. Closes #36

This PR request removes reference to old Bootstrap Bower package resulting in version 2.3.* being used for `css` option. It also reword test for `less` option to use `components-bootstrap` as name of package being tested - which cleans wording of tests for each CSS version supported (css/sass/less/stylus). Now the name of options, tests and packages are consistent with Bower names.
```
- use official Bootstrap Bower package
- update installation test for Bootstrap css version
- update wording of Bootstrap less component test
```
test:
```bash
Bootstrap generator test
    ✓ the generator can be required without throwing 
    ✓ installs bootstrap 
    ✓ installs sass-bootstrap 
    ✓ installs components-bootstrap 
    ✓ installs bootstrap-stylus 


  5 passing (35ms)
```