Added colour picker function to viewer

Added the method get_colour to the Viewer object. Returns a hsv
which can be passed into binary region finder. Wrote tests for the
new method. Also updated the readme file with some notes on how to use the
viewer.
Merge with master
Merge with master
Another merge with master, thanks Adam
Fixed lingering logger
Removed use of pkg_resources in test_viewer
Added matplotlib as a dependency
Syntax error
Remove logger import
Update README.md
Added missing return
Merge branch 'colour_picker' of https://github.com/thetestpeople/Geist into colour_picker
Fix repo location
Mark code as python
Merge pull request #29 from thetestpeople/colour_picker

Colour picker - looks good.