Implement Failed Messages indicator

[dannycohen]

As Opie, I want to be made aware in a timely manner of messages that failed to deliver

Visualization:

1. Failed Messages Indicator should be green if there are no failed messages
   • Definition of existence of failed messages: existence of failed message alerts whose status is "active" (see notes section below for details)
   • Number of active failed message alerts should be displayed in green under the indicator icon
2. Indicator should be red if at there are one or more active failed message alerts    * Number of active failed message alerts should be displayed in red under the indicator icon

Notes:

• Failed messages are not deleted from the database, but they may not longer be relevant and should therefore not impact the indicator status
• For this reason, we need to rely on the alert status in order to indicate whether a failed message alert is "active" or "cleared", and only indicate the number of active alerts

Demo / Acceptance tests:

Case 1:

1. Run the Video Store sample
2. Cause a message to fail (in the "Sales" endpoint)
3. The Failed message indicator is red, and the number "1 msgs in 1 endpoint" appears below it

Case 2:

1. Cause a 2nd message to fail (in the "eCommerce" endpoint)
2. The Failed message indicator is red, and the number "2 msgs in 2 endpoints" appears below it

Case 3:

1. Cause a 3rd message to fail (in the "Sales" endpoint)
2. The Failed message indicator is red, and the number "3 msgs in 2 endpoints" appears below it

[andreasohlund]

This is done