Decide on common resource reference syntax

[toumorokoshi]

context: #63 (comment)

Right now, aep.dev has a relative reosurce path that's acceptable for some references, while there's a full resource path for others.

It's a poor user experience to have inconsistency here. On the other hand, it's cumbersome to have to type the service name all the time, especially if your resource lives under the same service.

This is tracking ticket to decide on this pattern before we hit our GA / 1.0 milestone.

cc @rofrankel