Use grep checker in pdb checker.
Make files_for_commit return a list of strings.
Modify python_files_for_commit to use file command.
Enable pdb check for our repo (as it doesn't fail normally).
Merge pull request #27 from OddBloke/master

Use `file` to determine which files are Python files
Add test for files_for_commit.
Add pdb tests.
Optionally filter out files in pdb.
Merge pull request #30 from alexcouper/master-add-pdb-test

Master add pdb test
Add --version command.
Merge pull request #31 from alexcouper/master-version-output

Add --version command.
Rewrite the header of the pre-commit hook to use virtualenv python.
Only point at virtualenv Python if -e given.