Add `beef.debug()` function - wraps `console.log()`
Debug messages are suppressed for browsers which don't support `console.log()`
Update './core/*' to use `beef.debug()` instead of `console.log()`
Update './modules/*' to use `beef.debug()` instead of `console.log()`
Update './extensions/*' to use `beef.debug()` instead of `console.log()`
Add 'modules/debug/test_beef_debug/' module
