This prevents collisions with session attributes which may be set from
other servlets which were never removed.

After the transition to moving settings into the database, there were
numerous errors which occurred if a setting was not yet persisted. This
aims to fix that by being proactive about recognizing when a clean
install is done and registering all settings in addition to a new
method to persist a default setting if it is not yet registered.

Update input type to be of type date in order to get a calendar

Sometimes the sql query returns a Long instead of a BigDecimal. This
should prevent it from throwing an exception.

This replaces the old Maps for caching with a LoadingCache which
provides a simple interface for refreshing and evicting records. There's
probably still some improvement to be made but the sum/count queries are
fairly quick from my experience.