lua-console: make admin console work entirely under lua.

Integrate libyaml instead of internal yaml formaters.

changelog:
* fixed i64 convertion bug
* refactored bindings to new admin .info() scheme
* moved lua plugin api to separate file
* moved lua fiber api to separate file
* slab binding refactored
* added fiber lua bindings
* rewriten admin reply handler
* proper yaml end-of-document formater
* proper server error formater
* fixed bug with leftover data on stack on exception error
* added support of i64 types to lyyaml
* removed couple of box.show_ bindings
* console client fixes to support new scheme

This push has a yet broken test's.