google drive sync and logging

added logging functionality (CSLog) and made many improvements to
google drive sync (including intermittent network failure handling)
map view, ROI grid view, classifier bug fix

added pushpins to map view showing all exams w/ disclosure icons,
created ROI grid view which allows users to select + patches, removed
bug in classifier which set coordinates of overlapping regions to large
negative numbers. as a result, overlapping regions are now included in
analysis.