sophia: implement engine transaction; sophia transaction support

closes #gh-554
sophia-gh-577: make rollback procedure an engine related
sophia-gh-577: forge LSN on commit
sophia-gh-577: pass and use LSN during log recover, fix #gh-555

This patch uses sophia'a two-phase recovery to
integrate with tarantool wal.
sophia-gh-577: make profiler information available in tarantool
Merge branch 'master' into sophia-gh-577
Merge remote-tracking branch 'origin/master' into sophia-gh-577
sophia-gh-577: pass engine options on box.cfg
Merge branch 'master' into sophia-gh-577
sophia-gh-577: refactor txn engine statements
gh-577: review fixes
Merge remote-tracking branch 'origin/master' into sophia-gh-577
Minor edits of the comments.
sophia-gh-577: reduce number of engine methods
sophia-gh-577: do not emit raise on rollback
Merge branch 'master' of github.com:mailru/tarantool into sophia-gh-577