mogstored: Added stop function for HTTPServer

Due to the many children mogstored spawns cleanup work in DESTROY is not
feasible.
mogstored: stop functionality for nginx

Sends SIGQUIT on shutdown of mogstored for graceful shutdown of nginx.
mogstored: stop functionality for lighttpd

Sends SIGINT on shutdown of mogstored for graceful shutdown of lighttpd.
mogstored: Moved start for all servers after demonize

Otherwise the spawned processes are no longer children of mogstored
Tests: Add MOGTEST_MOGSTORED to start tests with 3rd party servers
Tests: Make fsck tests work with 3rd party Servers

This moves mogstoreds in their own process group and adds a Handler to
SIGINT/SIGTERM to cleanup the spawned mogstoreds.
Tests: change diag -> note to supress useless messages in non-verbose mode