* Allows the hyphen to be part of the field.

Hi, most json data I work with uses hyphens in the fields,  (jboss http management api) and I see that is valid json. 

I don't know if this is the best solution, but I think it won't choke on expressions as they should be implemented between back-quotes. 
So, this allows IDs to contain a hyphen (but not to begin with one).

thanks,