Bad color names in multi-label branch

[renxinhe]

olive and teal are not accepted color names. The third and fourth bounding boxes don't show up as a result of this. main.py line 19 need to be modified to include valid Tkinter colors.

[DennisFaucher]

Same

Traceback (most recent call last):
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 1547, in call
return self.func(*args)
File "main.py", line 296, in prevImage
self.loadImage()
File "main.py", line 223, in loadImage
outline = COLORS[(len(self.bboxList)-1) % len(COLORS)])
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 2337, in create_rectangle
return self._create('rectangle', args, kw)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", line 2316, in _create
*(args + self._options(cnf, kw))))
TclError: unknown color name "olive"