add support for submitting changes
improve assembly

- do not include libs which are already provided by intellij (smaller download)
- (almost) fix maven build (you need to change the scope of idea and forms_rt from provided to compile)
- custom build of ideauidesigner-maven-plugin is required for maven build: https://github.com/gshakhn/ideauidesigner-maven-plugin/tree/12.x
- update feature list im plugin.xml