Ignore .archive directory as a table

From a recent test run:

2012-07-22 02:27:30,699 WARN [IPC Server handler 0 on 47087] util.FSTableDescriptors(168): The following folder is in HBase's root directory and doesn't contain a table descriptor, do consider deleting it: .archive

With the addition of HBASE-5547, table-level folders are no-longer all table folders. FSTableDescriptors needs to then have a 'gold-list' that we can update with directories that aren't tables so we don't have this kind of thing showing up in the logs.

Currently, we have the following block:

invocations++;
if (HTableDescriptor.ROOT_TABLEDESC.getNameAsString().equals(tablename))

Unknown macro: { cachehits++; return HTableDescriptor.ROOT_TABLEDESC; }

if (HTableDescriptor.META_TABLEDESC.getNameAsString().equals(tablename))

Unknown macro: { cachehits++; return HTableDescriptor.META_TABLEDESC; }

to handle special cases, but that's a bit clunky and not clean in terms of table-level directories that need to be ignored.