Save wrapper function mongolastic.save(model, function(err, callback)

Added a save wrapper which solves the problem of lacking support of saveHandlers for mongoose. Added unit tests

Signed-off-by: Dominic Böttger <Dominic.Boettger@inspirationlabs.com>
version upgrade

[ci skip]

Signed-off-by: Dominic Böttger <Dominic.Boettger@inspirationlabs.com>