Changed to use getBool and fixed pagesize and offset handling.

Summary:
Simplified code and now pressing 'Hide/Show' button doesn't lose the
pagesize/offset information.

Test Plan:
Tested with different arguments in my sandbox. Tested that the old
'copies=true' and 'copies=false' are still working.

Reviewed By: epriestley
Reviewers: epriestley, jungejason
CC: aran, epriestley, tuomaspelkonen
Differential Revision: 318