Stricter games importer logic

[Fabrice]

Current
For each platform, PH try to import the last 1000 games, when error occured (for example a game against a computer, not a human) the game is skipped so you can end with less than 1000 games in database

Expected result
The number of games to import is global instead of applied to each platform. We expect to have imported the last xxx games across all the platforms. At the end of the import there should be exactly 1000 games in database unless there is not that number available via the apis