Conflicts:
	third_party/libyaml

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

I tired to type git clean blabla each time.

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

Requested by @kostja

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

Debian allows `adm` members to read logs.
Fedora/RHEL/CentOS don't follow this practice.

See also 93753cd0

Thanks @kostja and @unera for pointing it out.

Check evpipe[1] is the right way. Issue #1094.

See #1293

tarantoolctl must not search for configuration in
PWD if started by root

* Fix hardening if backtraces are off
* Ensure that all tests are passed with hardened flags
* RPM: add --with/--without backtrace option (default is --with)
* RPM: remove dependency on libbfd, libiberty, libz if --without backtrace
* RPM: enable stripping and debuginfo if --without backtrace

Backtraces are still enabled by default.

Hardened flags used by RedHat:

  -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
  -fstack-protector-strong --param=ssp-buffer-size=4
  -pie -fPIC