Gui enhancements

Hi, I wrote some small enhancements accordingly to https://issues.jboss.org/browse/HAL-265 

The contributions are:
- case insensitive filter and filter for text in the middle for: environment properties and deployed applications
- test datasource connection for domain mode (it is in runtime -> datasource)
- flush connection for domain mode (it is in runtime -> datasource)
- added help text to ctrl+click assign deployment to multiple groups