Add git_packbuilder_hash to query pack filename
Merge pull request #1949 from ethomson/packbuilder_oid

Add git_packbuilder_hash to query pack filename
Allow callers to set mode on packfile creation
Merge pull request #1952 from ethomson/packfile_mode

Allow callers to set mode on packfile creation
update example to new packfile creation signature
Merge pull request #1953 from ethomson/packfile_example

update example to new packfile creation signature