Resolve "exceeded visits list & unfinished visits list"

Closes #146 (closed)

added 16 commits

• 57d5b3ab - api that provides list of visits
• c25748b7 - counting of notification is done via django model query
• 05e189b6 - list of visits is visualized dynamically with pagination and sorting
• cb53c211 - visits and status api use common bool_to_str function
• a3145e2a - filtering by visit number added
• 560a7446 - debug output removed
• 54a6733a - common serialization function for subject and visit lists
• bb60eac5 - invalid field reference fixed
• b059fa6b - module reference fixed
• 6d8b017e - appointment types are available in visit list
• 7dd09c14 - appointment_type column in visit is filterable
• fda6f41e - list of columns for unfinished visit list defiend
• 487f1e8f - common serialize date methods extracted
• 33a5aff5 - unit test for visit sorting
• 9d1226f4 - unused code removed
• 75da6d99 - unit test for filtering visit data

Compare with previous version

unmarked as a Work In Progress

merged

mentioned in commit 5b7b917c