Added Facebook PHP SDK v4

The actual SDK files, located in vendor/facebook are not included
because they are not open source
Added login with Facebook
Added m\FbUser, better fb register

model FbUser extends User
When a fb user hasnt registered he is redirected to register/facebook
c\register@postFb will call FbUser::create, adding the user fbid to db
Create new pa account or connect old one to fb

Users will have the options to connect their existing PA accounts to
their Fb ones, so as to login with it.
Connect an existing PA account to Fb for login

Todo: able to disconnect if he has a password,
Set a password if he doesnt have one
Added disconnectFb, can set password if without one

To disconnect from Facebook, one must have a password set to log in.
Also renamed (dis)connectFacebook -> (dis)connectFb
Move fblogin functions to a new controller

Moved facebooklogin(), connectFb() and disconnectFb() from
c\API to c\FbLogin
Merge branch 'mvc+facebook' into framework

Conflicts: app/controllers/login.php
More keys at composer.json

Also fixed typo/bug at views/pending