Clean up all queries

There is a fair amount of inconsistency in the implementation of the database calls in the code. To improve maintainability, we should consistently use placeholders in the queries and fill them with the array argument to db_query rather than filling them in a string format above the call to the query.

To improve portability across databases, we should make sure that all inserts and updates are using dynamic queries rather than static queries. See https://www.drupal.org/node/310080