Node support: add package.json.

Modeled directly off of jquery.json; you can compare the two side-by-side and
see at the bottom the minimal changes and additions.
Node support: wire up Jasmine on Node too.

Re-uses the existing Jasmine spec; it's just modified to require() Mailcheck.
Node support: implement require() export!
Merge pull request #55 from aseemk/node

Node.js support!