Create test_switchdpidassignment.py

Regression tests to verify switch datapath ID assignment.
Update test_switchdpidassignment.py
use rcmd instead of quietRun when shutting down remote nodes
use ControlPersist ssh option to create a ControlMaster connection that will not die when a node dies
Fix typo in depend()
Only uninstall ntpd on COW disk.
IVSSwitch: turn off verbose logging by default

Most users don't need this much logging and it slows down the switch.
Merge pull request #447 from rlane/ivs-verbose-off

IVSSwitch: turn off verbose logging by default
Fix indentation error so we don't wait forever.
Merge pull request #241 from moijes12/fix44

(pending) Create test_switchdpidassignment.py
Some clarifications
raise exception when no prefixLen is set
Revert to old "Adding controller" message
Correctly call cli() rather than CLI()
Add setup() and dpctl() methods for LinuxBridge

Also adds docstrings.
Fixes #422
use isinstance( obj, basestring) to allow unicode strings

fixes #448
type( foo ) is bar -> isinstance( foo, bar )
Fix typo. ;-p
Fix undefined sleep()
Remove unused imports