refactored redis AR Query::scalar()
added revokeAll() test
RBAC documentation
Basic information about RBAC
Merge pull request #1300 from docsolver/master

Basic documentation about RBAC
added link to forum thread
Added link to new RBAC page
Merge pull request #1302 from docsolver/patch-1

Added link to new RBAC page
fixes #1303: Security::decrypt now returns null w/o error when null is passed as $data
indentation fix
added abstract function revokeAll()
revokeAll() implementation for DbManager
revokeAll() implementation for PhpManager
fixed Sort::params to be retrieved from Request instead of $_GET

for consistency with paginiation
some clarification on model docs
fixed Sort test
fixed array helper test
fixed travis and composer issue
fixes #1306
travis: speed up composer