GUI: support for super-dev-mode in GWT

- Super-dev-mode is necessary for GUI development in latest version
  of Firefox (>28) and Chrome. 
- Use cross-site linker necessary for super-dev-mode.
- Only devel version of GUI is set to use super-dev-mode, it's not necessary
  for production builds and doesn't affect them.

- Third-party scripts (like Re-Captcha), which needs to be loaded before GUI must
  use ScriptInjector in onModuleLoad() since they can't be part of gwt.xml now. This
  solution works in both versions.

Super-dev-mode benefits for now:
- no need for devel browser plugin
- faster recompile in dev mode (depends on app itself) 
- source-maps which points JS exceptions to places in your java code 

To run GUI in super-dev-mode, you must:

1. start codeserver (super dev mode build option in intelliJ)
2. visit codeserver URL and copy bookmarks for dev mode on/off (just once)
3. start regular web server (standard dev mode option in intelliJ)
4. visit regular web server url WITHOUT codeserver definition
5. click on bookmark "dev mode on"
6. recompile module by button in displayed webpage
7. ignore warning that it needs recompile and finally see running webapp

To see changes in code use bookmarks to recompile the module.
To see changes in html/css rebuild regular web server build.