Received NPE when configuring a single Filename (i.e. target/myapp.war)

This change enables users to configure URL's, Directories and Single Filenames as well. Configuration of a single filename resulted in a nasty NPE in the Logs and no deployment happened. I have added a Testcase to make sure the deployments are found in the future and a reference to powermock, because the method in question was findDeployments which was declared as private. If you are happy with the change, please accept the PR.

Buddy