[beeswax] Close HiveServer2 and Impala session command

  e.g. Close all HiveServer2 sessions created by Hue
  build/env/bin/hue close_sessions 0 hive

  e.g. Close all HiveServer2 and Impala created by Hue at least one week ago
  build/env/bin/hue close_sessions 7 all
[desktop] A user can share a document to a group he does not belong too
[filebrowser] Snappy decompression error should throw PopupException
HUE-2012 [core] upgrade django auth ldap
HUE-2012 [core] AD multidomain support

ldap_servers takes precidence over normal ldap config.
backward compatible since original ldap config can be provided.
Add server selection logic on front end.
Split tests by configs: test_ldap_deprecated and test_ldap.
The former will test deprecated configs and the later will test new configs.
The Synchronization middleware will choose the first LDAP Server
config when deciding which server to synchronize with.