Mention register_error_handler in errorhandler doc

The documentation for @errorhandler gives "app.error_handler_spec[None][404] = page_not_found" as an example for adding an error handler without the decorator.  However, register_error_handler appears to be the correct way to do this (added 0.7), and it eliminates the problems with modifying error_handler_spec directly.
Add Flask.config_class feature
Add ability to config from a JSON file
Update blueprints.rst - Error Handlers

Added information about custom error handlers in Blueprints with example based simple_page.
Update sessions.py

get_cookie_path: fix docstring
Add a non-decorator version of the error handler register function

The main application object has a register_error_handler function
which mirrors the decorator's functionality. According to the principle
of least surprise, make sure blueprints also have this convenience function.
Add tests for user-defined exceptions in blueprints
Fix test_no_error_swallowing

Path in assertion is now cross-platform.
Fix test_send_file_object

static/index.html now opens in binary mode, and therefore newline conversion does not take place.
Make the decorators attribute on View a tuple by default

To discourage accidental runtime modification applying to all views.
Merge branch 'master' of github.com:obeattie/flask
added missing import in sqlalchemy doc
Fix typo
fix typo (jsonfiy)
add TEMPLATES_AUTO_RELOAD option to config
Fix a typo on blueprints module name.
quickstart: import `request` in HTTP methods example
Update appfactories.rst, make extension related section clearer
Update url_for documentation

Previous documentation referenced a non-existent property on the Flask
object called "build_error_handler".

This should actually reference Flask.url_build_error_handlers.
Updated some typos

Fixed some incorrect variable references.