added explicit import to avoid "CertificateServiceImpl.java:907: error: reference to Extension is ambiguous"
Merge pull request #64 from surrim/ambiguous_extension

Disambiguation for x509.Extension
Implemented Command Factory such that commands can be implemented as
separate Command classes and registered at the CommandFactory.
Remove redundant .intValue() call.
Implemented /mode command for making mode changes. (Querying mode is not
supported yet.)
Modified /nick to use IdentityManager for nick changing.
Fine-tuned implementation for Msg and Nick command and unit tests.
Fine-tuned /me command and added unit tests.
Fine-tuned commands Mode, Join + added unit tests.
Improved CommandFactory implementation.
Added Jitsi license headers to some new files.
ICE4J revision 471: Fixes technical errors in method invocations. Optimizes type checks on packet send and receive.
jitsi/libjitsi commit 2a8891d47d877c867df1dad4674331beca095b00: Mitigates the general slowness and the occasional blockiness of the TCP socket writes.
Synchronize CommandFactory static methods that manipulate the command registry.
Use Jitsi /me display support instead of IRC formatting it itself.
Call listeners inside try-catch block to catch implementation bugs.
Removed TODO marker for unimportant task of which it is also not
immediately clear how to implement it.
Removed obsolete TODO

I originally added this TODO to suggest a nick name when adding a new
chat room. However, in the mean time I have decided to not allow nick
changes upon joining a new chat room, so this solution is now obsolete.
Fixed bug where command without parameters would not be recognized.
Log exceptions caused by command execution and added markers for improvements.