bump version 0.2.4-dev
    changed style of dict creation to work in python 2.6
remove deprecated WOF tests
also patch head requests for offline testing
make usgs.pytables docstring more informative
for each dataset module, pull major functions from core into module namespace
Merge branch 'master' of git://github.com/timcera/ulmo
run Travis CI tests python 2.6 as well
rm numexpr from setup.py requirements