Develop basic concept of event management

[azasypkin]

Scope:

• User should be able to set event handlers for the components;
• User should be able to connect events with actions;
• As the first step we'd like to:
  ** Change label name on button click;
  • Change button color on button click;
  • Change label background color on hover.

Dependencies:

• Introduce support of default properties and styles (Introduce support of default properties and styles. #14)
• [Events] Implement basic Action entity ([Events] Implement basic Action entity #13)
• [Events] Implement MessageChannel and Message ([Events] Implement MessageChannel and Message #12)

[azasypkin]

Scope has changed: we'll just cover basic event/event handlers infrastructure in this bug and return back once "Demo/Live" mode is ready so that we can test event handlers.