Version 6.7.0_PREVIEW_3.7.0-alpha.2_0

This is a preview release supporting API changes and new features introduced in ArangoDB 3.7.0-alpha.2.

• added overwriteMode parameter to support insert-update (ArangoDB v3.7)
• satellite graphs support (ArangoDB v3.7)
• schema validation (ArangoDB v3.7)
• added peakMemoryUsage to AQL stats