CS fixes
Added PsrHandler

This handler allows applications introducing Monolog to continue using
their existing PSR-3 compliant logger(s) in conjunction with the various
Monolog handlers available.
Merge remote-tracking branch 'michaelmoussa/psr-handler'
Make 5.3 compliant and faster call to wrapped logger, refs #437
Add install instructions
Merge pull request #3 from Seldaek/master

Update from origin