Refactored RequestOnSearchPeers to has-a for testabillity. #38
Extracts request on a single search peer from iterating over all of them. #124
Does not crash if a single distributed peer raises an exception. #124

All successful requests are returned.
Makes requests on search peers in parallel. #124
Doesn't add request responses if a request thread has been interrupted. #124
Creating new JsonRestEndpointCallers per request to peer. #124

Also new ArrayList() is used
instead of asList(), to create
a mutable list.
Removed unnecessary state from RequestOnSearchPeers with exceptions. #124