Merge pull request #715 from addyess/security/https-snapcraft

#715

#### Description

This PR switches the charmhub api connection from `http` -> `https` to make sure we're not insisting on `http` when calling charmhub and get blocked by firewalls.

#### QA Steps

We have tests in place to test the calls to charmhub, so all the tests in `test_charmhub.py` should be passing:

```
tox -e integration -- tests/integration/test_charmhub.py
```

#### Notes & Discussion

Note that this is only a temporary patch. There's gonna be a another PR that will fetch the host address from the model configuration dynamically.

Author: jujubot

juju/charmhub.py

@@ -21,15 +21,15 @@ def request_charmhub_with_retry(self, url, retries):
     def get_charm_id(self, charm_name):
         conn, headers, path_prefix = self.model.connection().https_connection()
 
-        url = "http://api.snapcraft.io/v2/charms/info/{}".format(charm_name)
+        url = "https://api.snapcraft.io/v2/charms/info/{}".format(charm_name)
         _response = self.request_charmhub_with_retry(url, 5)
         response = json.loads(_response.text)
         return response['id'], response['name']
 
     def is_subordinate(self, charm_name):
         conn, headers, path_prefix = self.model.connection().https_connection()
 
-        url = "http://api.snapcraft.io/v2/charms/info/{}?fields=default-release.revision.subordinate".format(charm_name)
+        url = "https://api.snapcraft.io/v2/charms/info/{}?fields=default-release.revision.subordinate".format(charm_name)
         _response = self.request_charmhub_with_retry(url, 5)
         response = json.loads(_response.text)
         return 'subordinate' in response['default-release']['revision']