fixes #1476 

Collections from blocked servers are crippled so that the map still appears to attempt loading.

To test (for example):
* comment out the entry for catami.org from Config.groovy
* delete or cripple catami.org from the database
* add  the Catami layer, from the AUV platform
allowedServer was a Map before now i have an ArrayList.
I agree it was neater and i tried to find a suitable replacement but i dont have the grails/groovy/java experience to come up with one