Fix lifestage tests.  They were incorrectly using datetime.utcnow().
Create the cache directory if it does not exists
Trailing whitespace / PEP8 cleanup
Loosen the paegan and GDAL requirements
Typo
Better error messages when a dataset does not have required variables
Better error checking for Bathymetry datasets
Remove the low_memory kwargs, it is useless now that the code is more l33t.
Avoid another data cache lookup if we don't need it
Document the Locks and Values
PEP8 Glory
GDAL 1.10 breaks, so only use the 1.9.x branches
Stop pickling the timevar, just pass it to ForceParticle.
Use fill_values in the NetCDF output.
Create export folders if they do not exist. PEP8 cleanup in export.py
Allow local datasets to be used without the DataController caching anything

Adds a 'caching' parameter to ModelController.run().
If True (default):
Data from the hydromodel is read and written
to a cache file by the DataController.  Particles read from that cache
file.  Useful for DAP datasets so you only download the same data once.
If False:
Data is read DIRECTLY from the hydromodel by the Particle, and the
DataController really does nothing.  Useful for local datasets.
Catch math.isnan values as well as None when aging a particle by age
Be sure to close the netcdf4-python dataset when a Particle is done
Add dependency on Paegan git commit
Merge pull request #15 from kwilcox/master

Bug fixes, test fixes, and some cleanup