* Switch to YAML instead of JSON
* Add utilites for replication
* Print test-run internal errors to console

Fill IPROTO_KEY for DELETE and IPROTO_TUPLE for INSERT/REPLACE.

- Update link to configuration files
- Change number of queries and data set size
[skip ci]

Delete the previous checkpoint in sophia only if we have a new one.

Actually fix the bug and add a test case.

closes gh-1428

Fixed double call of tuple_init_field_map in update and upsert operations, fixed comments of tuple_alloc

If `default_cfg` was nil, then system will errored.

* Don't mislead users with box.cfg{} options which shouldn't be
  set under tarantoolctl.
* Mention that all data directories must have absolute paths and
  remove work_dir from example.lua (see #1406).
* Specify correct default values.

+ closes gh-1405 (right path for unix socket)
+ wrap box.cfg and loadfile with pcall
+ some variable/function scope cleanups (global -> local)
+ closes gh-1409 (check for lua syntax before running/restarting/eval server)