Symfony 3 compatibility

Symfony 3.x Compatibility: (#6)

* Symfony 3.x Compatibility:
 - Updated usage of table helper (deprecated in 3.x) in commands to Table class.
 - Updated references to security context (deprecated in 3.x) to token storage.
 - Updated readme, should only register bundle in dev and test environments where it is intended to be used.

* Symfony 3:
 - Fixes issue with webdev toolbar when on anonymous access pages.