Switch airship's gerritbot channel

This switches the Airship project's gerritbot config to use the
new #airshipit-gerritbot channel, instead of the #airshipit channel.
This will help make sure conversation doesn't get missed in #airshipit.

Change-Id: I105b2e34b89fd2b3f13277731e90413d00baf78b

accessbot/channels.yaml

@@ -105,6 +105,8 @@ global:
 channels:
   - name: airshipit
     mask: full_mask
+  - name: airshipit-gerritbot
+    mask: full_mask
   - name: ara
   - name: cloudkitty
   - name: congress

gerritbot/channels.yaml

@@ -1,5 +1,5 @@
 # This file is sorted alphabetically by channel name.
-airshipit:
+airshipit-gerritbot:
   events:
     - patchset-created
     - change-merged