Remove strict procname dependency.

This fixes #80.

rq/worker.py

@@ -2,7 +2,11 @@ import os
 import errno
 import random
 import time
-import procname
+try:
+    from procname import setprocname
+except ImportError:
+    def setprocname(*args, **kwargs):  # noqa
+        pass
 import socket
 import signal
 import traceback
@@ -160,7 +164,7 @@ class Worker(object):
 
         This can be used to make `ps -ef` output more readable.
         """
-        procname.setprocname('rq: %s' % (message,))
+        setprocname('rq: %s' % (message,))
 
 
     def register_birth(self):  # noqa

setup.py

@@ -17,7 +17,7 @@ def get_version():
 
 
 def get_dependencies():
-    deps = ['redis', 'procname', 'times']
+    deps = ['redis', 'times']
     deps += ['logbook']  # should be soft dependency?
     if sys.version_info < (2, 7) or \
             (sys.version_info >= (3, 0) and sys.version_info < (3, 1)):