Issues post settings config

Hi this fix is to get around the 50 issue limit in Issue.jql queries.  Instead of converting to a post, I left it as a get.  I added optional parameters start_at and max_results to Client.  If not passed in they default to 0 and 1000 respectively.  I also added the ability to pass in start_at and max_results to Issue.jql it will override current settings in Client.

There was a little back and forth in the commits. from post to get and various other small syntax fixes etc.  Hope you find it useful.