Zoom hide

[onsah]

This PR adds the features mentioned in issue #39

Two new options are added:

• hideOnZoom: hides when zoom event occurs on cytoscape canvas.
• hideOnNonCyClick: hides when a left click occurs on all the document body.

Second option is useful when the app contains other clickable elements on top of the cytoscape such as menus. Example: Newt

[ugurdogrusoz]

I think the options are unnecessary. Let's hide the context menus in all operations such as zoom, pan, etc.

[onsah]

Yes that makes sense. In the current version options work by default and don't have or require any configuration.