Use python_daemon to daemonize devserver

[davidlmorton]

This is api-breaking, it now takes a daemondir argument instead of a
pidfile argument, because I needed to supply a directory for the stdout
and stderr file as well as the lock files associated with the pidfile.

[coveralls]

Coverage increased (+0.03%) to 3.16% when pulling 71e75db on davidlmorton:devserver_daemon into ecb0a4e on genome:master.

[coveralls]

Coverage decreased (-0.06%) to 3.06% when pulling bcf243f on davidlmorton:devserver_daemon into ecb0a4e on genome:master.

[mkiwala]

+1

[coveralls]

Coverage decreased (-0.06%) to 3.06% when pulling 61f5447 on davidlmorton:devserver_daemon into ecb0a4e on genome:master.