Check version on load / validation error

[gadicc]

Since the Yahoo API changes often, a lot of frustration could be avoided just by knowing a new version of the package is out. We could do this async on load, and/or, when showing validation error messages.

[z3nful]

This shouldn't be to hard to implement if we check package.json version against either github or npmjs, and we could possible add an option to throw a specific error if validation fails to tell servers running it to restart the process using the library and install the new version.