Incorporate recent changes into the master branch

[smmaurer]

I believe the ej-test branch is being used in some operational models. Let's open a PR to merge those changes into master, with some documentation in the PR writeup of what's been modified.

• PR of ej-test -> master with documentation in the writeup

Let's also begin including dev version numbers that increment with each PR -- this helps us track which version of the code is being used in a model.

• version = 0.1.dev1 in setup.py
• add __version__ = '0.1.dev1' to urbansim_parcels/__init__.py

And we can add a changelog while we're at it!

• create a CHANGELOG.md

See choicemodels or another recently updated UDST library as an example.

Can i assign this to @alephcero and/or @PyMap, with help if needed from @janowicz for figuring out what should be included in the PR and what the changes represent?