Add tsd.search.enable and tsd.search.plugin config option defaults
Add tsd.core.plugin_path config default
Add search object to TSDB
Add TSDB.indexTSMeta() and .indexUIDMeta() to access the search object
Add delete TSUID and UID search calls to TSDB
Add TSDB.initializePlugins() to load plugins and toss exceptions AFTER
construction of the TSDB
Add TestTSDB initialize plugins UTs