Add ability to install Orion plugins inside the Che editor

[azatsarynnyy]

In order to easily extend Orion editor functionality we need to add possibility to install Orion plugins for Che editor.

[JamesDrummond]

@vparfonov Provide status label.

[TylerJewell]

@azatsarynnyy - can you do a quick bulleted list of what the end user sequence might be like? Do we have a short example of an existing orion plugin that can be added into Che?

[azatsarynnyy]

@TylerJewell this task is needed more for us than for end user.
See Highlight Artik-specific keywords in the editor.
Also it may be used by plugins' developer for adding Orion plugin programmatically.
But, for now, there's no way for end user to install Orion plugin.