Fix Java 6 compatibility issue in test case

InetSocketAddress.getHostString() is Java 7 only, switching to .getHostName().
This may result in a PTR lookup, which shouldn't be a problem for a test case.
Unit tests for ZMTPFramingDecoder
Reject overly long identity values.

The spec states that identity values MUST be 255 octets or shorter,
let's enforce that.
Also, Let's test the funky overly long but explicitly allowed frame len format
Merge pull request #2 from noaresare/java6_fix

Fix Java 6 compatibility issue in test case
Merge pull request #3 from noaresare/framing_decoder_tests

Framing decoder tests
Merge pull request #5 from noaresare/reject_long_idents

Reject long idents