Automatically load kernel module dependencies

Before this commit, you'd have to manually insert the kernel module for
OVS or OF kernel modules, and you couldn't run one regression test with
all 3.

Now, these are kmod insert/remove is handled automatically.

INSTALL

@@ -47,12 +47,11 @@ Preliminary Mininet Installation/Configuration Notes
   To compile for Linux 2.6.33, you may need to apply the patch
   included below.
 
-  If you want to automatically load the kernel modules required
-  for OpenFlow, you could add something like the following to
-  /etc/rc.local:
+- Mininet will automatically load and remove kernel module dependencies for
+  supported switch types, using modprobe and rmmod - but these modules must be
+  in a location where modprobe can find them.
 
-    insmod /home/openflow/openflow/datapath/linux-2.6/ofdatapath.ko 
-    modprobe tun
+  See ~/mininet/util/modprobe_setup.sh for an example.
 
 - The reference OpenFlow controller (controller(8)) only supports 16
   switches by default! If you wish to run a network with more than 16