Add a link method to Thread

This will allow users to link their own callback functions to a
greenthread.

SHA1 of oslo patch: 9d3c34b59ac2e0246798c6db24b32c99f4196bd1

Change-Id: I5284ec0ccdbe093e6afff6511b19cf66f9356523
Ensure apt-get installs do not prompt user input

Set DEBIAN_FRONTEND to noninteractive and add dpkg options to ensure
apt-get installs do not prompt for input and cause the stack-create to
fail.

Closes-Bug: #1245899

Change-Id: I294783fb565b854143bc8a5d15834d8d88ad1a70
Merge "Add a link method to Thread"
Merge "Ensure apt-get installs do not prompt user input"