refactor release management command to work incrementally
change sitemap_indexed column from boolean to datetime
split release and update-sitemap into two commands: In progress
code to handle release command input tsv
set sitemap_indexed on batches and titles that have been indexed
Release command: Changed the key to look for in bag-info.txt
solr search by month/date: initial work
addresses #46: allow solr search by specific date, any year