Pull request

Good afternoon,

I really like the project, I have made the following updates:

Added overloaded constructor for StripeResponse to pass HTTP response headers
Updated contant name so it is uppercase: prettyPrintGson -> PRETTY_PRINT_GSON / gson -> GSON
Added more readable timeout values 30000 -> 30 * 1000 / 80000 -> 80 * 1000
Removed trailing comments (per Steve McConnel in "Code Complete")
Replaced StringBuffer with StringBuilder
instance variable should be generic Map type
Per Josh Block on Design Copy Constructor should be used over clone (StripeTest)
Refactored createQuery so it doesn't have to call queryStringBuffer.deleteCharAt(0);

Steve