SolrIndexSearcher's register do not match close and SolrCore's closeSearcher

1. SolrIndexSearcher's register method put the name of searcher, but SolrCore's closeSearcher method remove name of currentSearcher on infoRegistry.
2. SolrIndexSearcher's register method put the name of cache, but SolrIndexSearcher's close do not remove the name of cache.

so, there maybe lost some memory leak.