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Closes gh-871
Set aria-invalid attribute based on validation

As per http://www.w3.org/TR/wai-aria/states_and_properties#aria-invalid
the validation states should only be added after a user has had a chance
to enter a value
Add ARIA testing

Added new test suite for testing the ARIA-invalid features
Also added a few minor fixes for typos in the QUnit scaffolding and
JSHint errors
Fix "%o has no name assigned [object HTMLInputElement]" errors in bypassValidation tests
resetForm should clear any aria-invalid values
Initial ARIA-Required implementation

Add aria-required tags to any of the data, static or class required elements.
Dynamic validation for rules added through the form.validate rules object do not get picked up till first run.
Add build setup instructions
Add Instructions for getting the dist files

Moved remaining contributing instructions to Contributing guide
Fix require_from_group and skip_or_fill_minimum

Stops the require_from_group and skip_or_fill_minimum validation
methods from clearing previous validation rules on a form.

It does this by creating a cloned copy of the form's validator for
each group of conditionally required fields.  This validator is then
used to validate field group and is stored for re-use (fixes #412).
Add qunit tests for conditional validation rules

Updated tests for require_from_group and skip_or_fill_minimum rules.
The tests now check that other validation rules on the form are
enforced.