Ignore IDEA module files.
Introduce ignoringClasspath in SpringLiquibase.

This backwards-compatible change will allow to perform
"classpath:"-prefix comparisons between inserted changesets and
parsed changesets.

This can be useful in situations where Liquibase changesets are
executed with Spring and another plugin (such as Maven).
Merge pull request #187 from fbiville/3.0.x

Introduce ignoringClasspath option in SpringLiquibase.