- Bumped Sidecar version 0.2.2 -> 0.2.3
- Bumped RESTian version  0.2.1 -> 0.2.2
- Removed package_grant() from RESTian_Basic_Http_Auth_Provider.
- Renamed RESTian_Auth_Provider_Base->package_grant() to capture_grant(), changed from a filter-like function to an action-like function.
- Added a default RESTian_Auth_Provider_Base->get_error_message().
- Changed RESTian_Client->authenticate() to return a RESTian_Response and to handle error messages better.
- Changed RESTian_Response->error to RESTian_Response->_error and made private. Added get_error() and has_error() functions. Fixed set_error() to use $_error and to not fail when a null $message is passed.
- Improved the error message wording for BAD_AUTH for RESTian_Service->get_error_message().
- Removed unnecessary 2nd parameter from RESTian_Client->get_error_message() - parameter was a RESTian_Service object.
- Changed RESTian_Service->get_error_message() delegate to the auth provider if the API client didn't provide the error message.
- Renamed Sidecar_Plugin_Base->api to Sidecar_Plugin_Base->_api and made it protected and added a has_api(), set_api() and get_api() for access.
- Eliminated the $api_loader and $api_class properties from Sidecar_Plugin_Base and added a set_api_loader() method instead.
- Removed Sidecar_Plugin_Base->initialize_api() as we now depend on Sidecar_Plugin_Base->get_api() to initialize instead.
- Added a check for $wp_query->is_single and if not always returns true for  Sidecar_Shortcode->get_maybe_has_shortcode(). This can be optimized later.