Add cacheing of tables, columns, and injectables.
Switch simulation tests to use setup/teardown funcs.
Make sure fake_data_home is cleaned up after tests.
Remove old file and add pmat.py to .coveragerc.
Reset caches when replacing things in the registry

Includes: tables, columns, and injectables.
Merge pull request #80 from synthicity/sim-cache

Add cacheing in simulations
Add the ability to auto-save tables during simulations

By passing a file name and save interval to sim.run it will save
all the tables used by the running models to an HDF store every
X number of years. It doesn't save every registered table, rather it
saves only the tables that it detects are being injected to models
that are actually running. If models are using tables *not* via
injection those will not be saved.

If there's no year specified to run then the tables are just saved under
their names in HDF store. If there is a year the tables are saved under
keys like '<year>/<table name>', e.g. '2010/buildings'.

Note that the HDF store is opened in "append" mode so if there is a
pre-existing store with the same name you can get results from multiple
model runs in the same file.
adds the default formula to the columns needed for to_frame

also removing a small warning in sqft pro forma
deal with the case where model_expression is None
pep8
changing non-residential units to job_spaces
add building_sqft_per_job to developer

so res units and non-res units can be computed no matter which is being developerd (e.g. to account for mixed use buildings properly
Merge pull request #82 from synthicity/add-default-formula

adds the default formula to the columns needed for to_frame
Ignore NaturalNameWarnings from pytables

They come up when we store data under keys like '2010/buildings'
and warn that attribute access won't work (but key access works fine).
We don't care about this warning.
Merge pull request #81 from synthicity/save-data

Add the ability to auto-save tables during simulations
Merge branch 'master' into change-to-job-spaces
Merge pull request #83 from synthicity/change-to-job-spaces

Change to job spaces
Merge branch 'master' into remove-dataset-mdlrunner