Increase group timeout for AggregatorIntTests

https://build.spring.io/browse/INT-MAIN-561/

Author: artembilan

spring-integration-core/src/test/java/org/springframework/integration/aggregator/integration/AggregatorIntegrationTests-context.xml

@@ -47,7 +47,7 @@
 
 	<aggregator input-channel="groupTimeoutExpressionAggregatorInput" output-channel="output" discard-channel="discard"
 				send-partial-result-on-expiry="true"
-				group-timeout-expression="size() ge 2 ? new java.util.Date(timestamp + 200) : null"
+				group-timeout-expression="size() ge 2 ? new java.util.Date(timestamp + 500) : null"
 			    release-strategy-expression="messages[0].headers.sequenceNumber == messages[0].headers.sequenceSize"/>
 
 	<aggregator input-channel="zeroGroupTimeoutExpressionAggregatorInput" output-channel="output" discard-channel="discard"