Streams 132

Checking content in getMatches to ensure that it is non-null. Added debug logging statements to indicate when we hit a null content
My thought here was to catch any exceptions at the processor level to try and help narrow down where the exception was thrown and what caused it. However, in https://github.com/apache/incubator-streams/pull/55 I catch any processor exceptions in the StreamsProcessorTask class, so this try/catch may be unnecessary now