Make prefix work properly when querying and updating version

[knorrest]

Using prefix in project.clj doesn't work properly:

{:v {:prefix "MYPREFIX-v"}}

The problem is that the prefix is only added when creating a tag, not checked when querying for current version or updating the version. This PR fixes that by forwarding the config (and thus, the prefix) to the code that checks the version.

Side note - I was not able to run any tests.

[cch1]

I'll try to look at this tonight. Seems reasonable.

[cch1]

Also, regarding your side note: I'm finding that the tests fail on Java 11 due to fipp (a transitive dependency of midje). I've updated that dependency and now tests work on java 8 and java 11. Let me know what you see.

[cch1]

Unfortunately 27 tests are failing for me with this PR.