add. some validation and opts to add_cohort_data.
mod. Default request project to the one stored in usertags_meta.
mod. get_user to utilize query_calls for retrieving cohort users and id
mod. handle metrics call failures in agg and raw requests.
mod. Use a generator to return cohort IDs.  They may be fairly large and the option not to store the entire set in memory is useful.
rm. JOB_STATUS enum, deprecated.
rm. method to retrieve cohort users.  use method in query subpackage - get_cohort_users.
mod. rename user_registration_date to user_registration_date_logging
add. new query to retireve registration date from user table "user_registration_date_user"
add. method get_registration_dates to handle pulling registration data for users.
fix. pep8 compliance
mod. pass a start date to rev count query for threshold.
mod. make deault metrics logging more compact.
mod. Set dev status to "Development Status :: 4 - Beta"
add. method sub_tokens to substitute database and table names in query strings.
mod. ignore json and csv
mod. replace database (e.g. %(project)s) and table format elements in query_store entries with tokens to replaced by sub_tokens method.
mod. ensure escape_string in escape_var escapes a string without any whitespace.
fix. del connectons, use sub_tokens where instance and table names need to be substituted.  Remove stripping and splitting of SQL, unnecessary.
fix. secured rev_count_query and added test.