refactoring and cleanup views

- move common views to views/common directory
- move workspace views to views/workspace directory
- rename RequireJS dependencies to respect camel case notation
- remove temporary variable for defining and returning modules
- remove useless code
add scale, drag, resize support, closes #96

This commit greatly improves the UX in the workspace:
- resizing the workspace automatically scale down the content (i.e mouse, tooltips, etc.)
- drag and drop support is introduced
- resize support for tooltips is introduced