Allow default commit filtering to be editable

When releasing a Maven project with the mvn release:prepare command, the related commits are ignored by Bamboo.
This is OK for the first commit (starting with "[maven-release-plugin] prepare release"), but the second commit should not be ignored ("[maven-release-plugin] prepare for next development iteration").

The exclusion pattern is hard-coded as:

\\[maven-release-plugin\\].*

The following pattern would be more appropriate:

\\[maven-release-plugin\\] prepare release.*