Support gradle multiproject builds using a single build.gradle

We support both, a singleproject gradle structure (having a single build.gradle) as well as multiproject structures (having a build.gradle in the rootproject, and another one in the app (and all other dependencies) folder). However, I cam across a build that uses the root project's build.gradle to set a subproject's build information, e.g. look at https://gitlab.com/xphnx/twelf_cm12_theme/blob/master/build.gradle .

While the actual build currently works, update check is not.