[VOL-1913] Replies with errors of the form "transaction-not-acquired" are now ignored.

Also had to add a conditional branch in case no valid responses are received (the last thread to exit must clean up the connection).
The rw cores will now respond with a "transaction-not-acquired" error in place of "failed-to-seize-request" or COMPLETED_BY_OTHER.

Change-Id: I199d4a0091ba4fc1db5b8097adbad951408e5034
diff --git a/rw_core/core/adapter_request_handler.go b/rw_core/core/adapter_request_handler.go
index 2b28fa5..bd84bdd 100644
--- a/rw_core/core/adapter_request_handler.go
+++ b/rw_core/core/adapter_request_handler.go
@@ -72,7 +72,7 @@
 		log.Debugw("acquired-request", log.Fields{"xtrnsId": transactionId})
 		return txn, nil
 	} else {
-		return nil, errors.New("failed-to-seize-request")
+		return nil, errorTransactionNotAcquired
 	}
 }
 
@@ -93,7 +93,7 @@
 			log.Debugw("processing-request", log.Fields{"Id": devId})
 			return txn, nil
 		} else {
-			return nil, errors.New("failed-to-seize-request")
+			return nil, errorTransactionNotAcquired
 		}
 	} else {
 		log.Debugw("not-owned-by-me", log.Fields{"Id": devId})
@@ -101,7 +101,7 @@
 			log.Debugw("timeout-processing-request", log.Fields{"Id": devId})
 			return txn, nil
 		} else {
-			return nil, errors.New("device-not-owned")
+			return nil, errorTransactionNotAcquired
 		}
 	}
 }