i-bem: Think about debug module

[narqo]

[Guria]

Provide a way to put some additional debug code in js tech in none production environment. For cleaner output in production output such code should absent. Thought, it is not just about i-bem, this issue seems good place to hold this suggestion.

[qfox]

@Guria something like?

#ifdef DEBUG
console.warn('OMG FOO BAR')
#endif

[Guria]

Also auto console.log() of bem events, changing mod values, calling *SetMod handlers would be usefull.