Bug v0.2

This implements some features that didn't make the cut for v0.1 but are nonetheless useful to have, and fixes some bugs found in using v0.1 more heavily:

• added pre-commit sample hook to automatically save a copy of bug roadmap into a static file on commit (in hooks/ directory)
• added zsh command completion support file (hooks/_bug, need to put it in your fpath for zsh)
• Milestone sorting in bug roadmap will now attempt to sort with semantic versioning, instead of string comparison. If semantic sorting fails, it will try numeric sorting, and if numeric sorting fails, fall back to a simple string sorting.
• Added support for Mercurial in addition to Git. bug commit will detect what the current issues directory is tracked under and use the appropriate command.
• Fixed bug where bug commit would fail after a bug relabel (and vastly simplified the commit handling in doing so, also added some automated tests)
• Fixed bug where files that aren't directories would show up in bug list, but not be viewable.
• Added bug tag --rm option to remove tags
• Added bug list --tags option to include the issue's tags in the list output
• Improved handling of whitespace, so that bugs can now include a dash character and it won't be converted to a space in bug list

You can download the binaries for you Linux or OS X below. Extract them and put "bug" somewhere in your path.