Optimize Change Log, add entry for 2.1.4
Upgrade notes for 2.1.4
Update Downloads page

Even though it's useless right now...
Update GitHub "tags" link to new Releases feature.
Merge branch 'refs/heads/develop' into update/changelog

Conflicts:
	user_guide_src/source/changelog.rst
	user_guide_src/source/installation/downloads.rst
	user_guide_src/source/installation/upgrade_214.rst
Merge doc changes; small related updates.
Merge pull request #2524 from cryode/update/changelog

Fix & Update Change Log; add 2.1.4 info where necessary.