(Bug 5013) Add flag to prevent overwriting newly active icons' metadata

Adding a flag to show that an icon was inactive when the editicons form
was rendered.  We now double-check between the icon's status at commit time
and its status at page render time, so that if the icon was inactive at
either time, we don't update its values.
Merge pull request #435 from akpdw/bug5013-icon-metadata-vanishing

(Bug 5013) Add flag to prevent overwriting newly active icons' metadata
Fix number of tests
Add "slug" to the expected data structure
Adjust dimensions: we no longer add 50px padding
Add the parsing of youtube video urls to our embed output
Merge pull request #437 from afuna/failing-tests

Fix several failing tests