Improved Primitive support and better testing

This changeset addresses several issues.

- Improve primitive support so the status and output of an executed
primitive can be retrieved
- Merge latest upstream libjuju (required for new primive features)
- New testing framework
    This is the start of a new testing framework with the ability to
create and configure LXD containers with SSH, to use while testing proxy
charms.
- Add support for using ssh keys with proxy charms
    See Feature 1429. This uses the per-proxy charm/unit ssh keypair

Signed-off-by: Adam Israel <adam.israel@canonical.com>
diff --git a/modules/libjuju/examples/action.py b/modules/libjuju/examples/action.py
index 4a3cc6d..f839f11 100644
--- a/modules/libjuju/examples/action.py
+++ b/modules/libjuju/examples/action.py
@@ -7,7 +7,6 @@
 4. Waits for the action results to come back, then exits.
 
 """
-import asyncio
 import logging
 
 from juju import loop
@@ -27,8 +26,8 @@
 
 async def main():
     model = Model()
+    # connect to current model with current user, per Juju CLI
     await model.connect()
-    await model.reset(force=True)
 
     app = await model.deploy(
         'git',