Merge pull request #67 from christianchristensen/master

Group copy, join, copymembers and Event cleanup docs.
Adding SDKs and Plugins page with appropriate links to github and project pages.
Merge pull request #70 from arturo-c/sdks

Adding SDKs and Plugins page with appropriate links to github and projec...
Adding documentation for the ?offset flag.
Merge pull request #71 from icowley/gh-pages

Added notes on how the offset flag works.
Update group copy boolean defaults and explanation.
Update documentation on group join send_message parameter.