Make some white-box tests less flaky

If we want the *internal* state of the oplog driver to be consistent, we
need to make sure that we start our observes at a consistent point in
the oplog.  (ie, initial inserts need to have been fully processed, so
that we don't process them during the original QUERYING phase, which can
give us a different unpublished buffer.)

Note that only the white-box tests (looked at _unpublishedBuffer, eg)
appeared to be flaky: the actual docs published seemed to be correct in
all cases.
Merge branch 'devel' into release-0.7.2
Ensure that hook.each is called from a Fiber

That gives us enough guarantees that we can simplify the error-handling
code.

We also ensure that the "new connection" handler in livedata_server runs
in a Fiber, which fixes a bug introduced in d049bf7506 where connections
from pre-pre1 clients would crash (due to Meteor.setTimeout which only
works in a Fiber).
version bump examples and docs.
first cut banner and notices.
history tweak and version bump.
Note that connection is also passed to login hooks.
combine onLogin and onLoginFailure in docs.
update banner text
Document relationship between two validate hooks
update docs to real release.
bump version of examples.
Merge branch 'release-0.7.2'
Merge branch 'master' into devel

Conflicts:
	History.md