Made caniusepython3 as script. Fix #2.

This uses setuptools since it's the best option for making this work cross platform. This also actually tells pip/easy_install/etc to install the dependencies.
Made the short command line options show up in the help text provided by argparse.
Minor grammar edit

:)
Merge pull request #7 from JeffPaine/patch-1

Minor grammar edit
Merge pull request #4 from jezdez/short-options-help

Made the short command line options show up in the help text provided by argparse
Merge pull request #3 from jezdez/cli-tool

Made caniusepython3 as script. Fix #2.
Tweak some code formatting
Make main() less special-cased for __name__ == '__main__'
Everything is zip safe
Clean up output

Make the message very clear and properly handle single/plural cases
Add an explicit message when there are no blockers
Make the blocking list easier to read

Still needs tests.
Fix a broken test
Add an e2e test
Factor out pretty printing of blockers

Still needs tests
Add tests for pprint_blockers()
Explicitly list Python 3.3 as supported in setup.py
Try testing on Python 3.2
Figure out what is (not) blocking Python 3.2 support
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