Let surefire reuse test forks for Persistit
Rename TitanID.java to TitanId.java

Commit 97e6b0af8f738906957783717297490eed6b1289 renamed the public
class inside this file from TitanID to TitanId but did not rename the
file itself; this causes a compiler error ("class TitanId is public,
should be declared in a file named TitanId.java") so I renamed the
file to match the classname