Redesign of Login, Register and Recover Password

This PR implements the **new redesign for the login, register and recover password modal dialogs**.

The basic difference is that now we have different screens for Login and Register. Gem version has been upgraded to `1.0.5`. The first project to implement the new version will be the CMS.

The PR also includes a new `build_and_upload.rake` task to build and upload the gem to Gemfury.

Finally, note that the Sign in with Google button is not implemented, we've added it in order to test if people want to use it (it has Mixpanel tracking).

This is how it looks.

![captura de pantalla 2014-08-22 a la s 11 13 10](https://cloud.githubusercontent.com/assets/855995/4008859/93814a00-29dc-11e4-95eb-e531eefcbe90.png)
![captura de pantalla 2014-08-22 a la s 11 13 15](https://cloud.githubusercontent.com/assets/855995/4008860/959feeb8-29dc-11e4-8ee0-e09d5ee57160.png)
![captura de pantalla 2014-08-22 a la s 11 13 21](https://cloud.githubusercontent.com/assets/855995/4008862/982468b2-29dc-11e4-90bc-adfd13adade5.png)