Merge pull request #1 from nickcaballero/master

Appender-ref in logger
Merge pull request #2 from nickcaballero/master

Resource attribute for variable substitution

thanks nickcaballero for the contribution
Update src/main/xsd/logback_0.9.30.xsd

Added OFF to the levels pattern.
changed name of the XSD file to reflect that it covers more than just 0.9.30 of logback
Updated Logger to have a optional level and additivity attribute.
Allowed Appenders to have Elements not in a namespace.
Merge pull request #3 from bramp/master

Couple of changes to fix the attributes on Logger, and to make the Element processContents less strict.

Thanks bramp for the contribution!
Merge pull request #1 from enricopulatzo/master

Update