Log Message:
Update ejabberd to 2.1.10.

Bug fixes:

* Erlang/OTP compatibility
- Support Erlang/OTP R15B regexp and drivers (EJAB-1521)
- Fix modules update in R14B04 and higher
- Fix modules update of stripped beams (EJAB-1520)

* XMPP Core
- Fix presence problem in C2S after first unavailable (EJAB-1466)
- Fix bug on S2S shaper when TLS is used
- Prevent overload of incoming S2S connections

* XEPs
- BOSH: Get rid of useless mnesia transaction (EJAB-1502)
- MUC: Don't reveal invitee resource when room informs invitor
- Privacy: Activate "Blocked Contacts" to current c2s connection \ 
(EJAB-1519)
- Privacy: Always allow packets from user's server and bare jid (EJAB-1441)
- Pubsub: Add hooks for node creation/deletion (EJAB-1470)
- Shared Rosters: support groupname@vhost in Displayed Groups (EJAB-506)
- Vcard: Fix error when lowercasing some search results (EJAB-1490)