Merge pull request #5 from mtahmed/harris

Add edit command.
Merge pull request #9 from mtahmed/harris

Add paysoff command.
Colour-coding relevant amounts in the table red/green to identify owing/owed which fixes #6
Fixed condition bug from last merge regarding the same case and None vs. 0
Merge pull request #11 from mtahmed/fixconditionbug

Fixed condition bug from last merge regarding the same case and None vs 0.
Merge pull request #10 from mtahmed/colour-code

Colour-coding Owing Numbers
Edit command fix
Merge branch 'edit-comment' of github.com:mtahmed/balance into edit-comment