Investigate possible solutions for build number diffs on deploy

The "snapshot freeze" is a common practice during development: simply use a timestamped snapshot as dependency version instead of "-SNAPSHOT" ending one to "freeze" given snapshot deploy.

This works for simple cases (one dependency, or "aligned" reactor).

But take a look at Resolver itself: it has new-old and added-gone-readded modules, and their build numbers are different.

Problem is, that while timestamp is same (deduced from session start), the build number is determined from remote repository (deploy target) state.

This makes "snapshot lock down" impossible on long(er) running projects, like Resolver itself is.

PR adds -Dmaven.buildNumber=N support, that is still just "half solution", as one needs to figure out what N is (max+1 of all build numbers across all modules being deployed), but at least allows fixing the situation. WARNING: this requires caution, as number x needs to be DETERMINED first (should be max of existing build Numbers + 1).