Renaming the 'default' profile to 'common'

Following a recent modularity design decision, the 'default'
profile should be named 'common' going forward.  The special
meaning as a fallback when no module defaults are provided is no
longer in effect.

Resolves: rhbz#1658633
Signed-off-by: Petr Šabata <contyk@redhat.com>

ruby.yaml

@@ -115,6 +115,6 @@ data:
     # Add profiles/default as a temporary workflow,
     # because of a issue for omitted profiles element.
     profiles:
-        default:
+        common:
             rpms:
                 - ruby