Autodetect serial port

Hi Ricardo,

here are two commits for review, comments welcome!
##### Switching to nrjavaserial
I have had a lot of problems with the serial IO part, same as described by Chris [here] (https://github.com/3esmit/JObexFTP/issues/3). Original rxtx is completely useless on linux (SIGSEGV), cloudhopper frequently results in 0pointers in getall(). Next I tried the create-lab-commons and NRJavaSerial forks, both worked much better in windows. In linux, I did not get any of them to work, might try the nasty-serial branch next (another alternative could be purejavacomm, but that would need some code adjustement) the end I settled with NRjavaserial, as it is more recent and active. Another big advantage over the cloudhopper builds is that native libs are self-deployed.
##### Serial port autodetection
Basically,  I assume a TC65 to be detected when setting the device to AT_Mode does not throw IO/NoSuchPort/PortInUse