Implement the elapsed time timer

Signed-off-by: Jess Malvin Chin <jess@teamcodeflux.com>
Create the entry -> addon -> item relationships and include the creation form for adding items to entries

Signed-off-by: Jess Malvin Chin <jess@teamcodeflux.com>
Add entries_service that computes the total add on cost

Signed-off-by: Jess Malvin Chin <jess@teamcodeflux.com>