Add savanna-guestagent project

At the last design summit, we agreed to use guest agent in Savanna. This repo
will contain the first version (proof-of-concept) of guest agent implementation
for Savanna. It's a first step of unified agents approach implementation.

Separated ACL will be used for early dev / proof-of-concept period.

Change-Id: I68842135740cadb7d34b2f0889265239fe247dc1
Merge "Add savanna-guestagent project"