Fixes
Fix disableLogging()

Need to actually unset the header to properly disable access logs.
Adding functions to enable / disable Log-Retention

Can't use saveMetadata() like Container.php because of the name of the
header. Copied code from setStaticIndexPage()
Merge pull request #225 from slashterix/cdn-logs

Add functions to enable / disable CDN Access Logs
Merging PRs
Altering PR #225
Clarifying CDN container docs
Minor tweaks to getting started guide;
Clarifying getting started guide
Merge branch 'master' of github.com:rackspace/php-opencloud