CoreAdmin API does not handle config and schema parameters when persistence is enabled

Custom config and schema name are not written to solr.xml when persistence is enabled and CoresAdmin API is used.

For example:
curl 'http://localhost:8983/solr/admin/cores?action=CREATE&name=mycore&instanceDir=mydir&config=solrconfig-myconf.xml&schema=schema-myconf.xml&collection=mycollection&shard=myshard&loadOnStartup=true&transient=false'

In solr.xml there will be:
<core loadOnStartup="true" shard="myshard" instanceDir="mydir/" transient="false" name="mycore" collection="mycollection"/>

Solr will use default config and schema XML files, which may lead to some problems in querying and/or indexing.