Improve The README

[nsanta]

Currently, the README sucks. needs Improvements

[nielsjansendk]

If you could start with explaining how to get authorization to work for a canvas app, that would be awesome for me. I think this is a really great gem, good work!

[nsanta]

@ninajansen: Updated the expanation of how to use Canvas module for parse signed requests when the app runs as a facebook canvas app.

[rklubenspies]

Could you please provide an example of how to store a user's token and email in a database so that one could replace a typical brick and mortar login system with fbgraph (and a basic model to store a Facebook auth token). That way when a user logged in again all of their information would be remembered! An example like that would be much appreciated!

[andypalmer]

Storing a 3rd party id as a number, even if it looks like one, is bad practice. We don't need to do number-y things with the ids (mathematical functions etc)
(see twitpocalypse, http://absolutely2nothing.wordpress.com/2009/08/02/the-twitpocalypse-returns/ )

Rather than recommend that clients store it in a BIGINT column, I would recommend VARCHAR