Make browsable API views play nice with utf-8

Fixed a couple of small problems I found when using the action decorator.

Update assertion error to reference 'base_name' argument, not incorrect 'name' argument. Closes #933

Previously, using uppercase for the method argument would silently fail
to route those methods.

If you don't call it, it doesn't work.

Fixed minor typo in tutorial documentation.

Fixed typo in documentation (Testarea to Textarea)

Changes 'python' to 'Python' when used in prose.

Added test for custom fields with min_value and max_value validators

I was having problems with a custom field that used a min_value validator...

Typo