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/juju/unit.py b/modules/libjuju/juju/unit.py
index fc597bf..ce33b08 100644
--- a/modules/libjuju/juju/unit.py
+++ b/modules/libjuju/juju/unit.py
@@ -1,6 +1,6 @@
 import logging
 
-from dateutil.parser import parse as parse_date
+import pyrfc3339
 
 from . import model
 from .client import client
@@ -21,7 +21,7 @@
         """Get the time when the `agent_status` was last updated.
 
         """
-        return parse_date(self.safe_data['agent-status']['since'])
+        return pyrfc3339.parse(self.safe_data['agent-status']['since'])
 
     @property
     def agent_status_message(self):
@@ -42,7 +42,7 @@
         """Get the time when the `workload_status` was last updated.
 
         """
-        return parse_date(self.safe_data['workload-status']['since'])
+        return pyrfc3339.parse(self.safe_data['workload-status']['since'])
 
     @property
     def workload_status_message(self):