Added dataframe shuffler w/ test
Added watertight folds
Added tests for watertight folds; they don't all pass yet
Tests for shortcuts
Merge branch 'experimental-rewrite' of https://github.com/johnmcdonnell/ramp into johnmcdonnell-experimental-rewrite

# By John V. McDonnell
# Via John V. McDonnell
* 'experimental-rewrite' of https://github.com/johnmcdonnell/ramp:
  Added tests for watertight folds; they don't all pass yet
  Added watertight folds
  Added dataframe shuffler w/ test

Conflicts:
	ramp/folds.py