Reorganization of tank_vendor to support "vendor-less" shotgun-api3#914

mathbou wants to merge 4 commits intoshotgunsoftware:mastershotgunsoftware/tk-core:masterfrom

mathbou:feature/sg_api3_wihtout_bundled_libsmathbou/tk-core:feature/sg_api3_wihtout_bundled_libsCopy head branch name to clipboard