Function to get the ground-truth mask_rev1

This function returns a binary image where a circle of radius 30 pixels
is drawn is marked in white for each marked center in the ground truth.
getGroundTruthMask_rev2, ROI_thresholding_rev2

Updated ROI_threholding file with comments and evaluation code based on
the ground-truth.

The getGroundTruthMask file has only had the comments updated.
More efficient quantitative analysis

Added more efficient TP and FP computation. Added f1 score, percision,
and recall for quantitative analysis of the ROI detection procedure.
Added Comments

Added comments
Merge pull request #2 from foloumi/master

Updated ROI_thresholding code with quantitative analysis, created new funcion for ground-truth mask generation