#92 Public shares can be set to expire beyond max_file_life_days limit

[Tony Malkowski]

Summary: When creating a public shared file, the expiration date can be set past the max_file_life_days setting, causing the file to be removed before the expiration date has elapsed.

Expected behavior: limit date range in calendar ui widget to prevent dates too far in the future from being selected

Actual behavior: no limit on end date, causing files to be unexpectedly removed after max_file_life_days is reached