Add package.json draft.

Most aspects seem to be ok. The package name "evaporate" instead of
"EvaporateJS" was chosen, following npm's standard naming
conventions[3], but feel free to change that, of course.

[1] - https://www.npmjs.org/doc/json.html#people-fields-author-contributors
[2] - https://www.npmjs.org/doc/json.html#license
[3] - https://www.npmjs.org/doc/json.html#name
Merge pull request #24 from yamadapc/master

Add package.json draft.