Bug 279, 1390: Used Guava Cache r for lazy-loading of RPC Routers

Used Guava Cache for lazy-loading of RPC Routers, which
is thread safe. Guava Loading Cache was not suitable
since we needed to know when RPC was created outside
of Guava load() callback.

Introduced new internal exception type RpcIsNotRoutedException
which is thrown when service type is not routed.

Change-Id: I96b6ff68e300596aa837e21690f8cb92da12112c
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Merge "Bug 279, 1390: Used Guava Cache r for lazy-loading of RPC Routers"