produce version 1.2.3-19-axdf

[soloturn]

nemerosa should be able to count commits since tag or repo inception to produce an increasing number to give persons an easy way to judge what is newer. or is the idea in nemerosa to use a timestamp or seconds / minutes since 1970 for this purpose? which i guess would be fine as well.

[dcoraboeuf]

I've been thinking about adding this a feature for quite a long time, but could not find any decent period of time to act on this.