This implements a service for pointer verification. This makes the
slightly clearer, because it's not part of metainfo.
It also adds a peer identity cache which reduces database calls and peer
identity decoding.
Change-Id: I45da40460d579c6f5fd74c69bccea215157aafda
Metainfo method validateAuth checks things like API key, user permission
and rate limit but at the end all errors were returned as
rpcstatus.Unauthenticated.
Old Metainfo is not touched to avoid backward compatibility issues.
Change-Id: I78eb276210fc50151da58a5c84e13ecd0961da29
Move tests for old Metainfo API to separate file. Metainfo tests file is
large enough and in future it will be easier to remove old tests.
Change-Id: I9421907ef015a6dfa65f4de6ef01b2d2c8baa7df
