Prevent task loop at priority boundary (#554)
Prevent task loop at priority boundary (#554)

* Always include check to prevent randomly serving up tasks that the
user has recently worked on, rather than only performing the check when
requesting proximate tasks, as the same sort of task loop can occur when
a user is skipping the last task at a priority level
maproulette/maproulette2,Crashfreak/maproulette2,Crashfreak/maproulette2,mvexel/maproulette2,mvexel/maproulette2,maproulette/maproulette2,mgcuthbert/maproulette2,maproulette/maproulette2,mgcuthbert/maproulette2