README should use npm install ui-select

[anthonygarvan]

The issues forum is NOT for support requests. It is for bugs and feature requests only.
Please read https://github.com/angular-ui/ui-select/blob/master/CONTRIBUTING.md and search
existing issues (both open and closed) prior to opening any new issue and ensure you follow the instructions therein.

Bug description:

If you follow the readme, running npm install angular-ui-select, you get some older, unmaintained npm repo which is not compatible with angular 1.5+. Most newcomers will naively run npm install angular && npm install angular-sanitize && npm install angular-ui-select, which results in version incompatibilities.

Link to minimally-working plunker that reproduces the issue:

plunkr

Version of Angular, UI-Select, and Bootstrap/Select2/Selectize CSS

Running naive install with npm gives:
Angular: 1.5.5

UI-Select: 0.12.1

Bootstrap/Select2/Selectize CSS (if applicable): N/A

[user378230]

Whoops, I must have copied the bower one when I updated the README, can you submit a PR?