Introduce Patron version metrics in prometheus

[mantzas]

Is your feature request related to a problem? Please describe

In order to find out the version differences between microservices, we would like to introduce a counter that measures the services that are in a specific version of patron.
The counter should have a label that has the version of Patron in it.

Things to investigate:

• How do we get the version at runtime? Is there a way to know which patron module there is an which version automatically?
• Do we have to introduce a setup before making a version in Patron releases?

Let's talk before we implement something here.

[drakos74]

This might be a good starting point for this issue ... debug.BuildInfo (from Embed commit versions into binaries)

[mantzas]

Unfortunately, this is a package, not a binary, but i agree that we should either embed this a part of our release process (hardcoded of sorts)...