Fixed issue #132
Merge pull request #137 from mhorner7wd/master

#136 Fixed exception when image not found in imported extension
Updated AB dependency to 1.0.4
Fixed deprecated .getInstance() calls
[maven-release-plugin] prepare release DataCleaner-3.7.2
[maven-release-plugin] prepare for next development iteration
Upgraded Guava dependency
Added CONTRIBUTE.md file for potential contributors