Logo navigation + firstname/lastname Devise fix + Clean header

I've taken the extra links out of the header, added the Pulse logo to the top right (will send you to /clients if you are logged in) and fixed the Devise sign up so that Users are getting added with firstname and lastname. The "Hi, firstname!" now works. 

I'd like @mlttanaka to accept this pull request please. 

![](http://media.giphy.com/media/DLxaEcISD5TaM/giphy.gif)