Add Constants based on OpenCMIS
Add Constants based on OpenCMIS

Summary:
Add a Constants class that contains some
generic constants. This is based on the OpenCMIS
implementation. The constant names have not been
changed to keep in sync with OpenCMIS as much as
possible.

Reviewers: #forgetit-dev, claus.due

Reviewed By: #forgetit-dev, claus.due

Differential Revision: https://phabricator.dkd.de/D288

dkd/php-cmis-client