Added dist and build to .gitignore
Allowed zero and negative flows.  Bumped version to 0.1.1
Added function for converting between flow units
Added functions for calculating hyd gradient using Hazen Williams (HW) and
for converting between HW C and Colebrook White k_s
Bumped version in setup.py, removed unnecesary matplotlib dependency,
       added scipy dependency and cleaned up setup.py
Merge branch 'old_vers'

Conflicts:
	setup.py
Added a flag to force the use of Swamee Jain (i.e. assume turb flow ) in
friction factor calcs
Finished documentation of func for converting between flow units