File explorer real time content update

[dkulieshov]

User story

As a Che user I want to have actual content of project explorer irrespective of source of project structure modification.

Scenario

• User A creates a project P in a workspace W
• User A sees the project tree in a project explorer window in Che
• User A or user B ssh mounts to workspace W
• User A or user B modifies project P structure
  • Add/move/remove files/directories
• Modifications are done outside of Che by
  • IDE (Intellij IDEA, Eclipse, NetBeans)
  • CLI
  • File managers (MC, FAR, etc)
• Project P content is updated in a project explorer window automatically (no refresh needed)

[JamesDrummond]

@vparfonov Provide status label.