Creates a getMeasurementsSummaryMap in ReactDefaultPerf

=== Problem
ReactDefaultPerf has a printWasted function that uses console.table to show the results of the performance measurements.
PhantomJS doesn't have the console.table function, so it's hard to get the metrics and present them in a CI pipeline.

=== Solution
Create a ReactDefaultPerf.getMeasurementsSummaryMap that receives a set of measurements and just generate the summary map. 
This solution make possible to get the performance summary and format them as you like. Even using console.log().

```
// very simple example
console.log(
    Perf.getMeasurementsSummaryMap(Perf.getLastMeasurements())
);
`````

Space before the curly brace.