ACCUMULO-118 support multiple namespaces for tables

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/ACCUMULO-118@1489969 13f79535-47bb-0310-9956-ffa450edef68
ACCUMULO-118 merge trunk into sandbox

git-svn-id: https://svn.apache.org/repos/asf/accumulo/branches/ACCUMULO-118@1489980 13f79535-47bb-0310-9956-ffa450edef68