Consistent @since tags

Change them all to be relevant to this repo
Setup trafix
phpcs fixes
The plugin should be in require-dev, not require
Add a limit to find('list') calls

As highlighted in cakephp/cakephp#5398
Prevent fixture errors on postgres
Label as beta, not broken.
Convert plugin bake to "copy" a folder

Expect a folder "Plugin" in a bake theme - and render each file found in
it recusrively. Generate everything in this way, even empty files, so
that users can define a plugin template in a theme without having any
hardcoded files forced upon them by the plugin task itself.
Test fixes for the plugin task