remove duplicate code

There was twice a check for the Python version on OSX but the logging in the second step could never be reached.

src/bitmessagemain.py

@@ -20,8 +20,9 @@ import os
 import sys
 if sys.platform == 'darwin':
     if float("{1}.{2}".format(*sys.version_info)) < 7.5:
-        print "You should use python 2.7.5 or greater."
-        print "Your version: {0}.{1}.{2}".format(*sys.version_info)
+    	msg = "You should use python 2.7.5 or greater. Your version: %s", "{0}.{1}.{2}".format(*sys.version_info)
+    	logger.critical(msg)
+        print msg
         sys.exit(0)
 
 # Classes
@@ -41,12 +42,6 @@ import proofofwork
 
 str_chan = '[chan]'
 
-import sys
-if sys.platform == 'darwin':
-    if float("{1}.{2}".format(*sys.version_info)) < 7.5:
-        logger.critical("You should use python 2.7.5 or greater. Your version: %s", "{0}.{1}.{2}".format(*sys.version_info))
-        sys.exit(0)
-
 def connectToStream(streamNumber):
     shared.streamsInWhichIAmParticipating[streamNumber] = 'no data'
     selfInitiatedConnections[streamNumber] = {}