Update sprite-generator.py

Fixed the issue regarding colors starting with 0 REd and/or 0 Green.

Before: If the chosen rgb color value was something like:
RGB(0,255,32) or RGB(12,0,64),...
the finalized glyphicons generated was black

After: Every color you choose will be successfully interpreted.

Fix:

line 162: commented
          if pixel_data[x,y][0] < WHITE[0]:
line 163: corrected the new indentation
line 164: corrected the new indentation