Add Juju Public Key

This commit adds the requirement to provide the Juju public key to N2VC

- Updates integration testing to use public key
- Updates N2VC to accept juju_public_key and ca-cert
- Updated docstring of N2VC constructor

Change-Id: I4cad1f8c39024137a23060000d7502aad56ac644
Signed-off-by: Adam Israel <adam.israel@canonical.com>
diff --git a/tox.ini b/tox.ini
index c54d27d..481bb9d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,14 +14,18 @@
 [testenv]
 basepython=python3
 usedevelop=True
+
 # for testing with other python versions
 commands = py.test --ignore modules/ --ignore tests/charms/ --tb native -ra -v -s -n auto -k 'not integration' -m 'not serial' {posargs}
 passenv =
     HOME
+    VCA_PATH
     VCA_HOST
     VCA_PORT
     VCA_USER
     VCA_SECRET
+    LXD_HOST
+    LXD_SECRET
     # These are needed so executing `charm build` succeeds
     TERM
     TERMINFO