Automatically add cores found in skipchunk_data folder

[binarymax]

Solr cores are currently created by copying configsets to the skipchunk project inheriting folder, in skipchunk_data. When Solr is restarted, those cores are not "remembered" and need to be added to Solr again.

[epugh]

Think about using the API's that SolrCloud offers instead of the older "let me put magic files in magic dirs" to make things work.

[binarymax]

Yeah I'm quickly finding myself in a common situation of needing two different solutions for whether Solr is running in cloud mode or not :)

I probably just need to support cloud mode only.