Changing the check files for predictions due to backend changes
First try for cross-validation
Improving naming, formatting and fixing --cross-validation-rate related code
Adapting to method to function changes in bindings

- Adapts to the check_resource and get_resource_id functions that
  substitute the corresponding BigML methods
User locale used creating sources and new store flag

- Uses the user provided locale info to deduce the bigml.com locale for
  sources.
- Adds a --store --no-store flag to trigger the storage of every created
  or retrieved resource.
Updating docs with new locale, store and cross-validation-rate features
Adding tests for cross-validation, source locale update and store
Updating version to 0.2.2 and small typo
Adding --test-split flag to separate datasets in training and test
Test_split bug fixing, docs and new test
Adding new --ensemble flag
Cleaning and update version to 0.3.0
Refactoring compute_output function
Sparating evaluation and checkpoint module functions
Adding comments, minor fixes and refactoring checkpoint