Add read_timeout option

[gottlike]

Hi,

I'm using your wrapper to access the Adobe Survey API which sometimes takes a long time (minutes) to return data. In this case I need to specify a timeout for the connection that exceeds the default of HTTPI's 60 seconds. I changed the code locally, but it would be nice if you'd add that to the gem/library.

Thanks

P.S.: Thx for making this wrapper available to the public, it saved me a good deal of time!