Cosmetic adjustments for settings and version number

This adds only some cosmetics adjustments to the plugin like
- fix the version number displayed so that it reflects the version number in the changelog
- removes the old build options as they are obsolete now (and will be removed completely in another PR, the one for non-IDEA support)
- follows the convention for the changelog entries based on previous entries

@mtoader, do you think it would be nice to also change the plugin from ``` golang.org support plugin ``` to ``` Google Go ``` to be inline with the other plugins?

Note, I've tried to do it as part of this PR but then the ``` Execute Slave IDEA with plugin ``` would always start with a big error and plugins was getting disabled.

Thanks.