Update History, banner, notices
add line break in notices
tweak banner
tweak notices
Update docs and examples
Merge branch 'release-0.8.1'
Add v0.8.1 to History.md
Merge branch 'release-0.8.1'
Update docs and examples
Merge branch 'release-0.8.1.1'

The large number of conflicts is because release-0.8.1.1 was branched
off of release/0.8.1 instead of master.

Conflicts:
	History.md
	docs/.meteor/release
	docs/lib/release-override.js
	examples/clock/.meteor/release
	examples/leaderboard/.meteor/release
	examples/parties/.meteor/release
	examples/todos/.meteor/release
	examples/wordplay/.meteor/release
	scripts/admin/banner.txt
	scripts/admin/notices.json
Fix 0.8.1 regression in ROOT_URL with path

Fixes #2109.
Add credential secret argument to `retrieveCredential` functions.

Fixes #2118.
Unregister sessions from server when their heartbeats time out.

Conflicts:
	History.md
Update History.md
Make a History sentence more sentence-y
docs: turn off appcache on safari

Turns out AppCache on Safari 7 is totally broken (see
http://stackoverflow.com/questions/22888945/safari-7-application-cache-does-not-work).
This, combined with our "reload if you can't load CSS or JS" strategy for
multi-server deploy causes infinite reloads in some cases.

Hopefully this will resolve the sporadic complaints we get
from some users about infinite reloads.
Update banner and notices
Update docs to 0.8.1.2
Update examples to 0.8.1.2
Merge branch 'release-0.8.1.2'