Add in memory adapter with login ticket model.
Extract in memory storage to separate class.
Add Ticket Granting Ticket model for in memory adapter.
Add RubyCAS Util class.

Provided by @tpickett66
Add Service and Proxy Ticket for in memory adapter.
Add Proxy Granting Ticket for in memory adapter.
Require Util.
Merge pull request #6 from rubycas/in_memory_adapter

In memory adapter