`treehouses services novnc` (fixes #1779)

[fankaiyuan]

To do:

• [x] main functions
• [x] add icon

Set up:

In order to test novnc, we have to change the VNC authentication to VNC password, by default is UNIX password.

There are two ways to do it:

First way:

NOTE: reboot if necessary, there is a bug in treehouses vnc off #1780, run following commands exact once

1. if vnc already on, turn off the vnc treehouses vnc off; else go to 2
2. set up a password for vnc service mode vncpasswd -service
3. add the config by the following command

echo "Authentication=VncAuth" >> /root/.vnc/config.d/vncserver-x11

4. turn on the vnc treehouses vnc on

Second way:

1. turn on the vnc treehouses vnc on
2. access vnc via a realvnc viewer
3. click the icon on right top open the option tab change the authentication to VNC password and create a password

How to test:

• ./cli.sh services novnc install
• ./cli.sh services novnc up
• open a broswer and go to: <ip address>:6080/vnc.html?host=<ip address>&port=6080

[fankaiyuan]

#1786 Now set up can be done with

./cli.sh vnc passwd				#create vnc password for 'vnc passward' authentication
./cli.sh vnc auth vncpasswd		#change authentication to 'vnc passward'