Updated and cleaned up versions

This fixes https://github.com/flapdoodle-oss/de.flapdoodle.embed.mongo/issues/91

2.6.1 is the latest production release, with 2.7.0 as the latest development release. Deprecated all other versions.

Note that I assumed the tab characters were set to 2 spaces, but let me know if that's not right (why use tab characters?).

Also, I @Deprecated anything that wasn't the most recent production (2.6.1) or development (2.7.0) release. Let me know if that's not what you wanted.