add SplitLayer and Net::AddSplits to transform shared bottom blobs into
split layers
add split layer insertion tests; move split insertion code to util file
file models
everything in its right place
Synchronize GPU before CPU timers start and stop in net_speed_benchmark
Add Timer to wrap CPU clock_t and GPU cudaEvent_t based timing
Replace CPU timer with newly added Timer to benchmark net speed
Add state machine, boost::posix_time based cpu timer & tests for Timer
Fix the cpplint errors for benchmark Timer