Fix snapshot corruption in presence of concurrent updates introduced in 1.5.1-68

The final version of odnoklassniki patch did not include the
most important part - delayed free of salloc memory.

Make a quick & dirty fix to the point.
New Debian snapshot.
Backport UPDATE_OP_DELETE code from 1.6
Update tuple:transform to use multi-delete. Fix OPENTAR-64.
Use https path to git modules, git:// doesn't always work behind a firewall
Merge branch 'stable' of github.com:tarantool/tarantool into stable
Merge branch 'stable' of https://github.com/tarantool/tarantool into stable