added a unit test to make sure skll does not crash in cross-validation when there are rare classes that might only show up in a test fold
merged the latest develop branch, cleaned up unused imports
fixes for CV with rare classes: separated out creation of label dictionaries, added warnings, etc.
grid search folds are now configurable
check that the grid objective function is valid
Initial add of conda.yaml file
pep8
move check for grid objective to learner.train
Removed build string from conda.yaml
squashed a bug in experiments.py
Merge branch 'develop' into feature/configurable_grid_folds
test for invalid learner/objective combination
style corrected files
Add back missing entry points and add back build string.
updated test_skll.py
Merge pull request #173 from EducationalTestingService/feature/conda-yaml

Initial add of conda.yaml file
Merge branch 'develop' into feature/fix_for_cv_with_rare_classes
Merge branch 'develop' into feature/warning-tuning-objective
Merge pull request #174 from EducationalTestingService/feature/warning-tuning-objective

Feature/warning tuning objective
Explanation of tuning section for Iris example.