Normalize runtime threads in gantt chart

[effigies]

#3290 restored gantt chart functionality. The PR was generally delayed by a concern that the thread representation is misleading.

The proposed solution is:

if status_dict['runtime_threads'] != "N/A":
    status_dict['runtime_threads'] //= 100

I believe here:

nipype/nipype/utils/profiler.py

Lines 174 to 187 in 2e36f69

	status_dict = {
	"name": node.name,
	"id": node._id,
	"start": node.result.runtime.startTime,
	"finish": node.result.runtime.endTime,
	"duration": node.result.runtime.duration,
	"runtime_threads": getattr(node.result.runtime, "cpu_percent", "N/A"),
	"runtime_memory_gb": getattr(node.result.runtime, "mem_peak_gb", "N/A"),
	"estimated_memory_gb": node.mem_gb,
	"num_threads": node.n_procs,
	}
	if status_dict["start"] is None or status_dict["finish"] is None:
	status_dict["error"] = True

cc @shnizzedy