Set rel-indicator image on update
Responding to reviews: test modified to check for unchangedness, indentation
Fixed CI issue, card created - empty attrs in FF are null, not empty string.
Swapped double for single quotes
Merge pull request #218 from makyo/rel-icons-loadonce

To QA:

1. Start devel, watch the terminal
1. Deploy a bundle
2. Set one service in the bundle to 100 units
3. Watch terminal with simulator running; you should only see requests for rel icons when relation aggregatedStatus changes