Features/bower rails fix precompilation

Require proper path to Bootstrap's css file

```bash
$ rake assets:precompile
[WARN] table 'Role' doesn't exist. Did you run the migration ? Ignoring rolify config.
bower.js files generated
/usr/bin/bower install 
I, [2014-05-05T16:02:16.451046 #23524]  INFO -- : Writing /home/sergey/src/github/base/public/assets/application-65a02d73183acd6a13048c5e68b91805.js
I, [2014-05-05T16:02:16.602431 #23524]  INFO -- : Writing /home/sergey/src/github/base/public/assets/application-0eb780695e52843f39c559112861100b.css
I, [2014-05-05T16:02:16.622120 #23524]  INFO -- : Writing /home/sergey/src/github/base/public/assets/xray-1d0747cd9f5bc74e8910bb0ea83337e1.js
I, [2014-05-05T16:02:16.630791 #23524]  INFO -- : Writing /home/sergey/src/github/base/public/assets/xray-e19ecc75b331b67b5b84578ab76d2cf5.css

```

https://github.com/42dev/bower-rails/issues/79