This bails out of `cacheless_render` immediately unless the provided
text is present, since there's no point.
This is a slight improvement in our test performance. Across the
creation of 1,000 `Namespace` records, which caches the `description`
field and which is blank by default in its factory, this saves about
four seconds, which... sure. Why not.
This commit adds a number of _html columns and, with the exception of Note,
starts updating them whenever the content of their partner fields changes.
Note has a collision with the note_html attr_accessor; that will be fixed later
A background worker for clearing these cache columns is also introduced - use
`rake cache:clear` to set it off. You can clear the database or Redis caches
separately by running `rake cache:clear:db` or `rake cache:clear:redis`,
respectively.
The method Banzai::Renderer.pre_process would always be called,
regardless of whether the Markdown to render was already cached or not.
In cache the document _was_ cached the output of the pre-processing
pipeline was ignored resulting in it doing nothing but wasting CPU
cycles.
This commit moves Banzai::Renderer.pre_process into
Banzai::Renderer.render_result so that it's _only_ used when needed.
