migrates to MPS 2019.3.3

Update TravisCI config to use JDK 11

Fix preferences modification logic

Fix MPS group in build script

Add validation to Bitbucket Configuration Page

Migrate to 2018.3 and uptake newer mbeddr

Simplified configuration using repo URL, updated dependencies

Rename zipPlugin task to zipPlugins

Update travis.yml and build.gradle to publish zips

make sure that the UI is refreshed upon plugin load/configuration change