System Sampler should not change the sampler label if a sample fails
Use the responseMessage for error reporting
Simplify the code; the outer try block was not needed.
Bugzilla Id: 55462


git-svn-id: https://svn.apache.org/repos/asf/jmeter/trunk@1516154 13f79535-47bb-0310-9956-ffa450edef68