jre task should depend on any jars in the runtime classpath

[hakanai]

Fixes #130.

allDependencies returns a lazy collection which includes all the runtime dependencies. Those which come from projects will be a ProjectDependency along the lines of:

DefaultProjectDependency{dependencyProject='project ':lib'', configuration='default'}

This seems to make it run :lib:jar as part of the dependencies for the task.