Minor fixes and updates in tests

Author: cderici

tests/integration/bundle/bundle-include-base64.yaml

@@ -1,10 +1,12 @@
 series: xenial
 applications:
   ghost:
-    charm: "cs:ghost-19"
+    charm: "ghost"
     num_units: 1
   mysql:
-    charm: "cs:trusty/mysql-57"
+    charm: "mysql"
+    channel: "candidate"
+    series: "trusty"
     num_units: 1
     options:
       max-connections: 2

tests/integration/test_application.py

@@ -226,7 +226,7 @@ async def test_upgrade_charm_resource(event_loop):
 @pytest.mark.asyncio
 async def test_trusted(event_loop):
     async with base.CleanModel() as model:
-        await model.deploy('cs:~juju-qa/bundle/basic-trusted-1', trust=True)
+        await model.deploy('ubuntu', trust=True)
 
         ubuntu_app = model.applications['ubuntu']
         trusted = await ubuntu_app.get_trusted()