Styling issues

[manolo]

• Adding gwt styling rules and configured maven plugins so as we can check whether the code matches checkstyle rules. Right now those plugins are not run automatically because we have to fix many styling things.
• Added missing copyrights
• Removed CR
• Removed duplicated empty lines
• Removed trailing spaces
• Added NL at the end
• A lot of styling changes in order to avoid checkstyle-errors
• Run java-formatter on all source files to match gwt standards

[jDramaix]

LGTM