[FIXED JENKINS-18485] Use correct node permissions in remote API

From now on user needs:
  Computer.CREATE to use 'create-node' CLI command
  Computer.DELETE to use 'delete-node' CLI command
  Computer.CONFIGURE to use 'update-node' CLI command and its REST alternative
  Computer.READ to use 'get-node' CLI command and its REST alternative
[FIXED JENKINS-18485] Introduce Computer.EXTENDED_READ permission

    From now on user needs:
      Computer.CREATE to use 'create-node' CLI command
      Computer.DELETE to use 'delete-node' CLI command
      Computer.CONFIGURE to use 'update-node' CLI command and its REST alternative
      Computer.EXTENDED_READ to use 'get-node' CLI command and its REST alternative
[JENKINS-18485] Enable Computer.EXTENDED_READ permission using "hudson.security.ExtendedReadPermission".
Merge pull request #855 from olivergondza/node-permissions
Add forgotten @since from pull reguest #803