Modified how shuffling of training data is used

- Disabled shuffling by default
- Automatically shuffle if `grid_search` is specified
- Exposed the `shuffle` parameter to config files
Merge branch 'develop' into feature/fix_default_shuffle
Updated config files and tests for shuffling

- Modified custom learner config files to specify shuffle = False
- Modify summary tests to have 27 rows intead of 26 since the value of shuffle is now output in the summary
- Modify test_sparse_predict_sampler since its value changes because of the shuffling being turned off.
Updated config files
Documented shuffle option for config files.
Removed non-template config files.
Changed shuffling message to warning

- The warning is only printed out when `grid_search` is True but `shuffle` is not.
Converted shuffling message to warning in cross_validate
Merge pull request #190 from EducationalTestingService/feature/fix_default_shuffle

Updated default shuffling behavior for training and cross-validation
Merge branch 'develop' into feature/increase_test_coverage