Merged code from the slf4j extension by Matt Bertolini, so that now it is part of the core
Merge branch 'CORE-39' of https://github.com/cbotiza/liquibase into cbotiza-CORE-39

Conflicts:
	liquibase-core/pom.xml
	liquibase-core/src/test/java/liquibase/resource/UtfBomAwareReaderTest.java
Merge branch 'cbotiza-CORE-39' into 4.0.x