v0.5.0 - gyms leaflet

A quite big update for the beginning of the week! This one brings support for gyms, as well as new map engine.

NOTE: you need to run db.Base.metadata.create_all(db.get_engine()) once again in order to create two tables, forts and fort_sightings. Your sightings table will be left alone. Moreover, you also need to run a migration on sightings - please apply migrations/v0.5.0.sql on your database manually. If you use something different than MySQL and SQLite, modify the migration to suit your needs.

List of changes:

• support for gyms
  • they are stored in fort_sightings table
  • they are displayed on live map, too
  • gyms.py contains a page with gym stats that can be shown to public - see https://pogowroc.modriv.net/ for example
• switched to Leaflet for live map engine
  • as an user you will probably say "ugh, it's so ugly" (and I'll agree), but as a developer it's much, much more comfortable to work with than Google Maps
  • overall it should be faster (including drawing worker circles)
  • you can dynamically toggle Pokemon, trash and gyms layers
  • Pokemon fade out as they are going to expire
• it's possible to display Pokemon names with different locale (credit goes to @Noctem)
• Pokemon icons on /report are clickable, and redirect to species report (credit goes to @fxbt)
• encounter_id in sightings table