Implement the rest of the Venues API

[leikahing]

Add complete support for the Venues API, for the following endpoints:

• /venues/add
• /venues/explore
• /venues/managed
• /venues/search
• /venues/suggestcompletion
• /venues/timeseries
• /venues/VENUE_ID/herenow
• /venues/VENUE_ID/similar
• /venues/VENUE_ID/stats
• /venues/VENUE_ID/dislike
• /venues/VENUE_ID/edit
• /venues/VENUE_ID/flag
• /venues/VENUE_ID/like
• /venues/VENUE_ID/proposeedit
• /venues/VENUE_ID/setrole
• /venues/VENUE_ID/setsinglelocation