Adds history collection module for FF privileged JS

Third try is a charm. I made sure I actually pushed the right code this time :)

Verification

- [ ] get a shell through a firefox javascript privilege exploit, like `exploit/multi/browser/firefox_proto_crmfrequest`, using `set TARGET 0` to use a js shell
- [ ] `use post/firefox/gather/history`, run it against the above session
- [ ] you should get a json file containing all the history currently  saved in firefox