When we print output in console (especially in Lua mode)
it is impossible to find out the internal type an entry
represents, which in turn leads to inability to encode
"ULL" entries properly. Moreover we always introduce new
types (for example decimals, uuids) and the serpent module
we currently use for encodings has no clue about them.

Thus lets implement own lua serializer similarly to the
yaml encoder. This allows us to properly detect every
field and encode it accordingly.

Part-of #4682

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>