Test against wtforms2
Create Meta in a WTForms2-compatible way

Allow each class Meta to be a subclass of its base class' metas. This
allows changes to the base classes to propagate via normal inheritance
logic, also the Meta isinstance of all the other metas.
Attribute definition order preserved in generated form, refs #41
Tests for field order, refs #41
Bumped version
Added numeric type scale to decimal field places conversion
New doc structure
Added title
Bumped version
Form fields generated now in class initialization time rather than object initialization time.
Bumped version
Add not_null_validator and not_null_str_validator config options
Update validator docs
Update config docs
Merge branch 'wtforms2-support' of https://github.com/crast/wtforms-alchemy-work into crast-wtforms2-support

Conflicts:
	tests/test_configuration.py
	wtforms_alchemy/__init__.py
Update changelog
Bump version
Update WTForms-Components requirement
Remove WTForms-Components from test matrix
Added failing test case for #46