works with geoglows 2

Merge pull request erdc#30 from erdc/flake8

Flake8 & Pylint fixes

to version 2.5.2

version to 2.5.1

- @spence97 added additional return period generation methods (gumbel…

… & log-pearson)

- Jim Lewis added CMIP5 support
- Added pangaea to determine time from files where possible
- Added option to run single folder in simulation

use pytest as nose is deprecated; move docs requirements to setup.py

made netcdf4 package lowercase

removed dowload url

various fixes for weight & voronoi

added optional arg for mpiexec command