New N2VC interface + updated libjuju

This commit introduces the Python3 N2VC module, which acts as a standard
interface to the VCA.

The goal of this is to provide a common way for modules to interface
with the VCA.

- Updated libjuju from 0.6.1 to 0.7.3

Signed-off-by: Adam Israel <adam.israel@canonical.com>
Change-Id: Ide70fb5ae5797eb6486de24653dc09a23f9c009e
diff --git a/modules/libjuju/docs/upstream-updates/index.rst b/modules/libjuju/docs/upstream-updates/index.rst
index 52099e6..7082a6e 100644
--- a/modules/libjuju/docs/upstream-updates/index.rst
+++ b/modules/libjuju/docs/upstream-updates/index.rst
@@ -1,5 +1,5 @@
-Upstream Updates
-================
+Syncing Upstream Updates
+========================
 
 Updating the facade and definitions code generated from the schema
 to reflect changes in upstream Juju consists of two steps: