Promise.irregardless

Based on a reddit discussion, this adds the following functions to the Promise prototype:

• Promise.prototype.irregardless
• Promise.prototype.regardless
• Promise.prototype.always

All of these are just aliases for Promise.prototype.finally, and thus you may need a shim to provide that.

ES3 is not supported.

Preserving any remaining sanity of any potential users is outside of the scope of this project. You have been warned.