chore(grunt): switch from git-changelog to grunt-conventional-changelog

The previously-implemented git-changelog module for automated changelog generating was buggy and seems like it's not being actively maintained, so the bugs are unlikely to be fixed soon. After doing some Googling, I found Brian T. Ford's grunt-conventional-changelog, which seems to be everything I was looking for, and it does it without the bugs (for as far as I can tell so far).
chore(npm): update a few of our Node dependencies

Since it's been about 6 weeks since I last worked on this, a few modules we depend on have been updated. I upgraded all of the ones that looked safe to upgrade and will investigate upgrading others later. Will revert this commit if it turns out this breaks things.
Merge branch 'dev' of https://github.com/xiehan/sinead

Conflicts:
	package.json