Merge pull request #58 from dvanliere/master

Two minor fixes to improve bash scripts on OSX.
Fix .so file generation error introduced lately
rdkafka_performance: -X topic... properties did not work
rdkafka_example: Added -X prop=val
examples: Added support for canonical "end","beginning","stored" to -o offset arg
Added salebab's phpkafka to list of users
Log OP_ERR right away, without need for poll, if no error_cb is set.
Added simple timers
Added consumer offset management (local file)
The application no longer needs to ignore SIGPIPE
snappy clang compilation fix
Allow producing and consuming empty messages (issue #60)
Fixed ftruncate compile warning on gcc-4.6
Added more configuration API functions


rd_kafka_[topic_]conf_dup() - duplicate config object
rd_kafka_[topic]_conf_destroy() - destroy config object

rd_kafka_[topic_]conf_dump() - dump configuration values to string array

rdkafka_example: added '-X dump' switch to dump configuration objects.
Remove SIGPIPE handlers, no longer needed.
Added configuration tests
Define MSG_NOSIGNAL for OSX.