Publish imposter to Maven central

[Hi-Fi]

It would be nice for testing if importer would be available in Maven central and it could be handled same way as other (test) dependencies.

[outofcoffee]

Added instructions on where dependencies are published and embedding steps in 5e351da5.

[Hi-Fi]

Plugins (inclufing openapi mentioned in embedding steps) seem to be missing from there.

For Maven I think it would be best to create separate plugin, that allows to kick the server up directly from pom.xml. Of course server can be started already with the exec-plugin, but that's not so clean as I would hope.

Of course the plugin doesn't need to be part of the imposter repo itself, but would be nicer that way.

Also for OSS it's free to use Sonatype's Maven repository, so if there's no some specific limitations I think it would be much better than some self made repo (https://central.sonatype.org/pages/ossrh-guide.html).

[CedricMtta]

Hello, that would be great and ease usage in some company environment :)