Do not load menu item just before determining context handler to prevent premature access denial due to empty og context.

[jummonk]

Issue in og_context.module, function og_context_determine_context().

When determining the context, don't by default load the menu item and just test on current path. Because if during the custom menu access check og_context is called (as can be the case in a views access plugin or ctools access plugin where og_context would be called), then the statically cached initialized context will seem empty.
Solution is not loading the menu item before determining the context, thus preventing a custom access being executed which could in turn execute og_context() to establish a context, resulting in denial of access as the context is initialized alrready, but empty.