Started using samples_generated from sklearn

- Modified `make_regression_data()` to use `samples_generator` from sklearn
- Modified `test_regression1` to FeatureSets in memory instead of writing files.
Removed the mean, min and max tests
PEP-8'ing the code.
Removed commented out/old version of make_regression_data
Added regression test with feature hashing

Reorganized the unit test for regression to test regression both with and without hashing.
Updated test_predict to use sklearn samples_generator
Merge branch 'develop' into feature/fix_unit_tests
Modified how intercepts are returned and fixed regression tests
Merge branch 'develop' into feature/fix_unit_tests

Conflicts:
	skll/learner.py
	tests/test_skll.py
Merge branch 'develop' into feature/fix_unit_tests
Qualified checks for grid_objective

- Modified learner.py such that the check for grid_objective being valid only happens if grid_search is set to True.
Specify feature_hasher in check_predict for train and predict
Replaced assert equality checks with eq_
Merge branch 'develop' into feature/fix_unit_tests
Updated grid objective function validity test

Now allows function types 2,3 and 4 for regression models
And checks for class types in classification models
Adds a simple backoff in case the classes are of mixed type
Added tests for regression grid objective funcions

Needs to be extended for classification case
corrected 'type-2' list
Modernized test_summary

- Modified make_summary_data to use make_classification
- Reorganized test_summary and check_summary_score to run both with and without feature hashing in a single function.
Fixed tests to work with python 2.7

- Converted rounded numbers to ints for python 2.7
- Used assert_almost_equal instead of eq_ in test_summary since python 2.7 thinks `0.5666666666666667` and `0.566666666667` are not equal. Sigh.
Merge branch 'feature/fix-grid-objective-check' into feature/fix_unit_tests

Conflicts:
	skll/learner.py
	tests/test_skll.py