Add micros/macro average F1 to TestDiscrete

[danyaljj]

Whenever we use TestDiscrete it prints something like this:

[info]  Label   Precision Recall    F1   LCount PCount
[info] -----------------------------------------------
[info] false       96.874 100.000 98.412  61178  63152
[info] true       100.000   0.804  1.595   1990     16
[info] -----------------------------------------------
[info] Accuracy    96.875    -      -      -     63168

I am suggesting to add micro averaged scores (simply averaging F1, Precision, etc for each label) and macro averaged scores (which are calculated across all labels). This would save some time later.