more testing with different planner options

Issue #34 still needs work
Added option None in Obstacle tab

and added if statements to catch if obstacle is set
if obstacle has been unset insure it is no longer set by setting to None
State Validity Checker now has a default value

If nothing is passed, the state validity checker gets set to an always
True lambda function. This allows for reseting the obstacle tab back to 
None. It also seems to be working again in all my recent runs?

This closes #34