Fix for JSSC crash (file handler leak)

[cmaglie]

Here the fix:

scream3r/java-simple-serial-connector#36

We must wait for the upstream author to merge and release a fixed version.
Alternatively we can drop a custom build of the library on the next Arduino release.

[cmaglie]

The library has been fixed upstream.
Upgraded to jssc 2.8.0.

C