Camel endpoint for SMSlib v4

Hi!

This pull request contains the following additions:
* Basic implementation of a Apache Camel endpoint
** Endpoint can be modem or mock based gateways
** All incoming messages are mapped to Camel Exchanges and all headers are preserved
** Outgoing messages are supported but quite bare (Just send the Exchange's body as string - that's it)

This pull request contains the following changes:
* Added optional dependencies for RXTX/java comm to help users to find the correct dependencies
** "Replaced" RXTX dependency with https://code.google.com/p/nrjavaserial/
*** Compile compatible with RXTX but does the native library loading on-the-fly during runtime (extract to temp folder)
* Refactored mock test gateway to also send messages (for Camel endpoint testing)
* Improved reflection code for javax.comm calls to preserve complete stacktraces

Let me know if you have any questions,
Sebastian