Merge pull request #31 from Ecotrust/master

Fix some ZeroDivision errors and Geometry problems
update test file
Update README.md
delete unnecessary files
add try/except if routing fails
Add option to not use helicopter logging

Closes Issue #242 in Ecotrust/land_owner_tools
minor fix
additional test data
Add option to only load and haul a proportion of the total volume
Update main_model.py