Ignore some properties

[etrange02]

Hi!

First of all, this library is very nice to use! It is so easy to request Janusgraph with it instead of other libs.

I am facing a problem with my models : some properties must not be added into GraphSON data. I set schema.default = none.

So, I wonder if a GraphsonIgnoreAttribute can be an interesting addition.

Thank you,
David L.

[danielcweber]

This unit test shows the way.