Updating gems and fixing errors and deprecation warnings

Fixes https://lib-jira.ucsd.edu:8443/browse/DHH-305:
* upgrading to blacklight 4.7, hydra-head 6.5.0.rc2, active-fedora 6.7, solrizer 3.1 
* replacing extra_head_content with content_for(:head) in views
* replacing delegate_to with has_attributes (with datastream and multiple params)
* avoiding generating RDF subject URIs with blank PIDs
* including Hydra::AccessControls::Permissions instead of Hydra::Datastream::RightsMetadata
* replacing render_pagination_info with page_entries_info
* replacing render_head_content with yield(:head)
* using .to_s where TermProxy was failing to be a String
* removing most calls to reindex test records
* replacing .new? with .new_record?