h2 database locking mechanism changed to FS from SOCKET

https://github.com/sonatype/nexus-pro/pull/423
http://www.h2database.com/html/advanced.html#file_locking_protocols

Nexus uses H2 databases for NuGet and User Token storage. Nexus uses SOCKET locks to protect the database. The default lock encouraged by H2 now is FS type locks.

We expect that FS type locks will be more reliable for our ITs because random ports do not get opened we cannot control. FS also has several other advantages.