Implement consistent hashing common methods

Implement consistent hashing functions and add unit tests.

These will be used by each conductor service to determine
which nodes it is responsible for, and by each API service
to determine where to route RPC requests for specific nodes.

Change-Id: I6d6ae987e76e2d11f8f3f8843800a17d8ff1aaa0
bp: instance-mapping-by-consistent-hash
Merge "Implement consistent hashing common methods"