Tidy up log calls in event

This reduces the category of some noisy log events, adds a category to
those missing one, and removes a number of commented-out calls.
[Log] Provide a default log category for Y.log calls

Set a default log category of info if no category was specified, or the
category specified is not in the list of valid categories.
[core] Fix coverage tests

The original coverage tests used yui-core-coverage and loaded the rest
of yui-base by inserting script tags. This seems to have been set up
that way to get more granular coverage information than just one entry
for yui-base, but it is causing YUI.add to fail in certain cases because
Loader is not yet available. This changes the coverage test to do the
same as the regular unit tests.
[core] Add missing `yui` module to coverage tests
use visibility:inherit to allow overlays to be hidden
update change log
Document app.showContent as chainable
Merge remote-tracking branch 'solmsted/patch-1' into live-docs
[app] Build

min files are no change.
[docs] Mock data for AutoComplete YQL example
[docs] Mock data for AutoComplete Geocode example
Merge branch 'dev-master' into dev-3.x
Merge branch 'dev-master' into dev-3.x
Merge remote-tracking branch 'andrewnicols/event-touch-loglevel' into dev-3.x
[event] Build
[event] Update HISTORY.md
Merge remote-tracking branch 'jafl/calendar-visibility' into dev-master
[calendar] Build

min files are no change.
[calendar] Update the history
Merge remote-tracking branch 'andrewnicols/ylog-missing-categories' into dev-master