Refactor logging to use psr3

[Emlyn West]

Update the logging interface to accept psr3 style logging.

[Emlyn West]

https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-3-logger-interface.md

[Frank de Jonge]

@stevewest I've made the DBAL logging aware so this is supported, you should look into that.

[Emlyn West]

@FrenkyNet I saw your comment on irc, it is what prompted me to do this. Just ironing out a bug and this will be finished.