Finished MPLViewer and connected it to plot

This Closes #15

in MPLViewer:
- implemented MPLViewer
- based on MyStaticMplCanvas and pathVisualization ompl tutorial

in sdp_project_demo:
- added numpy and StringIO imports
- changed Window Title
- connected plot button, no longer static plot
- added plot function to plot self.path
- TODO: ensure self.path exists

in MainWidget:
- changed from MyStaticMplCanvas to MPLViewer object

in KinemamaticCarPlanning:
- getPath() now returns path asGeometric as suggested in ompl doc for plotting
- modified test when running as script
- imported Numpy and StringIO

in MyStaticMplCanvas:
- newline at end of file