Use a plain MIT license, so the code is open source, but add a prominent advisory notice about complying with voting laws and avoiding misuse of the code.

* ADVISORY.md: New file, warning users not to misuse the software.

* LICENSE.md: Plain MIT license now, with pointer to ADVISORY.md at end.

* README.md: Don't repeat license text, just refer to LICENSE.md.
Run through `fmt -w 78` and rename
Add ref to LICENSE
Minor copywriting
Add README
Remove state-specific info now that it's likely out-of-date
Merge branch 'remove-state-reg-data' into license
Merge pull request #28 from democrats/license

[WIP] Use standard OSS license, accompanied by an advisory notice