Update intercom.js

A combination of the following fork updates:
- https://github.com/brandid/node-intercom/commit/148a1a95bd1ba179e025b0ad031d1e8d6c44c210
- https://github.com/viktors/node-intercom/commit/9f52c13e1a73bbc72267148671a4e076ad8571f4
- https://github.com/ksullivan/node-intercom/commit/8123d5ef524a202e657629b1e2602bedd04c41aa

Also, tag implementation from https://github.com/clippPR/node-intercom.