fixes to schema.mysql.sql

### create table players_names()
added collate utf8_bin to player_name

Since you would have duplicate entry problem for example MICHAËL BOURNIVAL & MICHAEL BOURNIVAL in mysql.

### create table teams()
Added primary key and unique to longname and play_abbrev. Else you can't reference them as foreign key in create table games_plays_players() (Errno 150).