ACCUMULO-1537 fixing tests and timings, migrated visibility test

git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1499414 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-1481 : Add tests for splitting/merging root table; refactor to consolidate metadata constants and structures in an organized way; begin consolidating metadata ops into a servicer interface to abstract the code that actually does the servicing of metadata for all tables; remove some special cases for checking for metadata tables/root tablet that no longer apply; make mock work with root table; fix SimpleGarbageCollector to confirm candidates for deletion by checking the root table as well as the regular metadata table


git-svn-id: https://svn.apache.org/repos/asf/accumulo/trunk@1499510 13f79535-47bb-0310-9956-ffa450edef68