Added portion to clean mask
Reworded a doc string.
Added function to clean cc mask
NF: New function to clean coarse corpus callosum segmentation.
RF: Restored thresholds.  Moved full corpus callosum segmentation to end.
BF: Added newline at the end of the file.
Merge pull request #252 from klchan13/clean_cc

Clean cc
Merge branch 'upstream_master'