The BOINC manager should display the build SHA1 in its About dialog

[brevilo]

Showing the arbitrary build version isn't enough to know exactly the source code version used for a build. Show the abbreviated SHA1 of the HEAD used for building the app in the dialog as well.

[ChristianBeer]

This is needed to better distinguish development versions without creating a new minor release just for a limited test.

[brevilo]

The Android app can be changed in a pretty easy way. I'm going to open a PR for it soon.

Alternatively the client itself could have the SHA1 compiled in (use git describe to fetch the details) and a new RPC (?) added such that the manager can query it. This assumes that manager and client are compiled from the same source though.