Planner API examples updates

3.1.2 release

SharePoint model updated to 16.0.24106.12014 version, a few import fixes

Fix for AuthenticationContext.acquireAppOnlyAccessTokenWithCert metho…

…d: recognize site context

SharePoint API: service root url fix for web resource

OneDrive API: createFolder function fix

v3.0.0 release

Merge pull request #299 from mogic-le/readme-php-version

Drop PHP 5.5 requirement from README, replace with PHP 7.1

SharePoint API: file/folder addressing enhancements

Optimize odata request payload serializing, fixes for saving multi-ch…

…oice field value (#261)