Adds the ability to add filters to a Facet in a multiselect Facet, see Solr Documentation

###Sitecore Version and Search Tested on Sitecore 8+ with Solr.

###License Copyright © 2016 Kyle Kingsbury

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an 'AS IS' BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.