Improving documentation

As Hakan Dilek asked me, I improved the documentation to explain how to use GlobalCRUDSetting class. This is the first commit (1acbcca). 
I then added few improvements that would have helped me.

Since my english is far from being perfect, this all should be reviewed. Sorry for the typos.

In the Custom DAO and CRUDController, I added a line for the use of the @Inject annotation that may be required for the constructor to work. I added it because reading it could have saved me a lot of time and headaches, but I don't know if it has to be in the documentation.

Feel free to correct, drop or asking me to improve anything.