Fixes Zarel/Pokemon-Showdown-Client#278 (weather prediction bug)

Fixes weather prediction inaccuracy bug when
- When weather is changed by ability on the first turn
- When weather is changed by ability on switch after a Pokemon faints
The value of <code>summonerMoved</code> should default to <code>true</code> and be changed to <code>false</code> in the assignments below to properly mirror whether the pokémon has moved or not.