Clean-up setup.py some more.
Iterate over a copy of locals.

This way we don't iterate over a dictionary that we are actively
changing.
Clean up __init__.py files.

This simplifies the files, as well as fixes problems on import on Python
3.3.
Add configuration for Travis.
Add current Travis status to Readme.
Merge pull request #1 from metpy/travis

Add Travis CI testing.