Merge AbstractSortedSearch into AbstractSearch

[lindyhopchris]

There's no requirement to have both AbstractSearch and AbstractSortedSearch - it would be simpler to merge the child into the parent. If someone wants to implement their own sort method, they can always override the sort method anyway.

Searching can be disabled by not allowing the client to send any sort parameters anyway - i.e. through the request definition.

[lindyhopchris]

Closing as this is available via Componser on the v0.5.x-dev release