Extend bob version information

[ikopylov]

1. --version parameter should additionally print commit hash from which the binary was built
2. Bob version should also be available from REST API (version + commit hash)

[ikopylov]

It is also required to include backend (Pearl) version to the output. We found a problem that an old version of Bob was unexpectedly built with a new version of Pearl, so we need a way to diagnose such problems in the future.

If possible, it would be nice to include commit hash for Pearl as well.

Additionally, it would be nice to include build time to the output of --version.

For the REST API the output should be JSON with Bob version, Pearl version and build time.