HBASE-12110 Fix .arcconfig

Summary: Not many people are currently using arc but it's a nice tool for the developers who are used to it. Since it's already there let's make it work.

Test Plan: If this works then it's tested.

Differential Revision: https://reviews.facebook.net/D24075
HBASE-12111 Remove deprecated APIs from Mutation(s).
HBASE-12079 Deprecate KeyValueUtil#ensureKeyValue(s).