[fixed] updating a model will no longer unindex the model on attributes that
weren't updated. Thanks to https://github.com/mayfield for the bug report,
analysis, and initial pull request that ultimately resulted in the fix.
[fixed] pip requires, versioning, etc., thanks to fixes from
https://github.com/mayfield
[changed] Model.get_by() will now work on any type of indexed columns. Unique
columns work as before, and other columns get pass-through to the
Model.query interface.
[changed] Model.get_by() and Model.query.filter() will both accept single
numbers as the value to match on (you don't need to specify a range if you
are querying by equality).
[changed] all changes will be documented in this changelog.txt file to keep a
list of everything that is going on with the project.