improved how "show more" link looks

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

affected, replaced onClick handler with onMouseUp/Down to detect text
selection not trigger onClick handler then

now return empty hash instead of throwing a 404 error. When following,
merge into timeline will filter statuses

This was broken in c3e9ba6a, which added an onBlur to hide the
suggestions when the textarea loses focus. Unfortunately, this fired
even when the textarea lost focus to its own suggestions box, and that
meant that onSuggestionClick is never called.

Setting a short window in which onSuggestionClick can still happen
before hiding the suggestion area ensures that clicking still works,
while still hiding the suggestions if the user clicks on something else.

Also, since the root component connects to the stream that updates home/notification columns,
there is pretty much no case for refreshing those columns beyond initial load. So, move the
loading of those columns into the root component, to prevent unneccessary reloads when switching tabs
on mobile or resizing desktop window between mobile/desktop layouts

application website validation, don't link to app website if website isn't set,
also comment out animated boost icon from #464 until it's consistent with non-animated version

with YAML-defined defaults. Add admin page for editing global settings. Add "site_description"
setting that would show as a paragraph on the frontpage