Suppress warning on `taxit update` of `tree_stats`

Warning will still appear when using the API.
Merge pull request #66 from fhcrc/no-warn-on-taxit-update

Suppress warning on `taxit update` of `tree_stats`
CHANGES
remove gh-pages submodule
- Makefile adds html/.nojekyll
- Use current year in copyright
- fix docstring
- add instructions for development
- add requirements.txt
installs xlrd
update CHANGES