Made columns that store strings intended for humans of type Unicode.
Removed import of 'Index' constructor, using package-qualified name instead.
Removed text import as well, limiting non-module imports to SQL types only.
Replaced unnecessary coding declarator with minimal docstring.
Merge pull request #6 from edelooff/model-updates

Model updates
Added a Resource base class and resources required for customer collection and single object.
Define ACL on the root.
Added case transformation functions for JSON <-> Python conversion.
Added a parent and name to the root resource.
Added an API error resource which can be used to raise specific errors.
Removed error_code from JSON error response, this duplicates the HTTP code.
Added handlers for Colander validation failures and generic API errors.
Added schema loader and first colander schema for login.
Updated session API to use defined schemas.
Fixed bug where the object resource was loaded instead of the collection.