Use Jython's PosixModule to grab process id for mcservl.

Jython relies on jnr-posix to provide a "POSIX emulation layer" on a
wide variety of platforms (AIX, FreeBSD, Linux, OS X, OpenBSD, Solaris,
and Windows).
Merge pull request #64 from jon4than/servermanager_getpid

Use Jython's PosixModule to grab process id for mcservl.