Adding error builder convenience constructor

- creating category
- adding new keys to AppTranslator project file
Adding recovery attempters convenience constructors

- adding block recovery attempter convenience constructor
- adding alert recovery attempter convenience constructor
- changing alert recovery attempter delegate method as in issue #8
- removing mr_didRecovery
Several fixes for builders created with errors

- adding facebook keys to builder's userInfo
- avoiding to add keys not present in the error's userInfo
- changing underlying exception pattern to strong
Podspec like CocoaPods/Specs@b9359ef
New imports

- adding MRErrorBuilder+NSException.h
- adding ErrorKitDefines.h to example's pch
Documenting some methods