Conflicts:
	doc/www/content/newsite/careers.yml

Added 2 new sections to chapter 6. Server administration:
(*) 6.5. Notes for systemd users
(*) 6.6. Updating Tarantool in production

Fixes gh-1243 Clarify database operations description to take into account multi-statement transactions

This reverts commit d72fd069.

Tested and updated building instructions for Mac OS X. (by Elena Shebunyaeva)

Revised the entire tutorial (file help_en_US.lua):
 * Tested and fixed all sample code snippets.
 * Corrected typos and inconsistent names in screen headers.
 * Updated info about custom delimiters (screen #6).
 * Replaced box.session with fiber (example on screen #10).
 * Swapped screens #11/#12 (fibers/sockets) for smoother story flow.

Removed help-related stub logic (file help.lua).

Updated auto-tests to expect a new output result on help call.

https://release.debian.org/migration/testing.pl?package=tarantool:

Trying to update tarantool from 1.6.3.539.g211672f-1 to
1.6.7.551.ga5bafc5-1 (candidate is 25 days old):

+ tarantool/amd64 unsatisfiable Depends: binutils (<< 2.25.90.20151126)
+ missing build on XXX: tarantool-common (from 1.6.3.539.g211672f-1)