Automatically delete queries from DB, or provide cleanup function

[Ed McDonagh]

Each time a query is made, a new row is added to the study and series tables, which is never used again and is not deleted.

Could delete it immediately - not sure if it would mess up the display?

[Ed McDonagh]

Added a query.delete() 10 seconds after the C-Move has been marked as complete. Tested, works. Fixes #311

→ <<cset b89584cf1d36>>

[Ed McDonagh]

Updating changes. Refs #311

→ <<cset 646df306b4bd>>

[Ed McDonagh]

Doesn't delete queries where the move never takes place