Changed remaining refs to netns to refer to mnexec.

.gitignore

@@ -1,2 +1,2 @@
-netns
+mnexec
 mininet.egg-info

mininet/net.py

@@ -105,10 +105,10 @@ def init():
         # Perhaps we should do so automatically!
         print "*** Mininet must run as root."
         exit( 1 )
-    # If which produces no output, then netns is not in the path.
-    # May want to loosen this to handle netns in the current dir.
-    if not quietRun( [ 'which', 'netns' ] ):
-        raise Exception( "Could not find netns; see INSTALL" )
+    # If which produces no output, then mnexec is not in the path.
+    # May want to loosen this to handle mnexec in the current dir.
+    if not quietRun( [ 'which', 'mnexec' ] ):
+        raise Exception( "Could not find mnexec - check $PATH" )
     fixLimits()
 
 class Mininet( object ):