load moar issues

 * we have repos with more than one page of issues
 * tested with single page and more pages, on gihub enterprise
 * no clue about behaviour with errors
 * parsing json before caching now, so the issue pages can be merged
   into a single entry before caching the result
 * defaulting to one page to not change current default behaviour
Merge pull request #36 from fctechno/moar-pages

load moar issues