Added equality methods for vectorizer and featureset

- Two vectorizers are equal if they have the same datatype and the same vocabulary.
- Two featuresets are equal if their ids, classes, features and vectorizer attributes are equal.
Fixed bug in checking array equality
Update featureset __eq__ and added tests

- Updated `__eq__()` in featureset.py to ensure that the shapes are also equal.
- Added `test_equality()` in test_featureset.py.
Added zero padding to feature names in fake data

- Modified `make_classification_data()` and `make_regression_data()` to use zero padded feature names so that they are sorted correctly.
Updated test_featureset.py

- Modified test_equality to add test when everything else except the feature names are the same.
- Updated all other tests to use zero-padded feature names.
Fix bug in skll_convert

- Fixed bug that was not splitting the string before iterating over it.
Modified featureset `__eq__()`

- Modified definition of featureset equality such that instead of asking that the feature values be exactly identical, we now simply check that they are the same up to five decimal places.
Updated test_utilites.py

- Added new skll_convert test that tests the `--reuse_libsvm_map` flag.
- Updates other tests to capture the STDERR and print it out.