Change 'isGranted' view helper config.

Remove 'helper_mapper' key from 'view_manager' config. Rename 'isGranted' factory in 'getViewHelperConfig'.
Configuration file sample
Merge pull request #38 from jmleroux/config

Configuration file sample
Merge pull request #36 from francisdaigle/master

Change 'isGranted' view helper config.
unit tests
Merge branch 'master' into identity