Add TypeScript type definitions (#50)

* Updates dependencies to latest version

* Add type definition

* Update README to use constructor form

Since according to source, it's preferred. And so that it matches the first example.

Ref: https://github.com/18F/private-eye/blob/db8fb3ed8d2cd2e4273b0c006f50c52084a493c6/private-eye.js#L48-L50

* Update tests to use constructor

Include backwards-compatibility confidence check

* Options aren't optional

ignoreUrls is explicitly required, else `Array#forEach` will throw: https://github.com/18F/private-eye/blob/db8fb3ed8d2cd2e4273b0c006f50c52084a493c6/private-eye.js#L68

* Bump version to 2.1.0

Co-authored-by: Sarah Withee <2601974+geekygirlsarah@users.noreply.github.com>

bump to v2.0.0

bump to 1.1.0

scope the NPM package to the organization