Jenkins: Set up 'system_tests_quick' job for LXC-based execution

 * Remove all 'sudo' calls from system_tests_quick
 * Add interpreters to system_tests_quick scripts
 * Remove 'install sandbox' script from system_tests_quick

   A sandbox image is pre-installed in the seed.

 * Use pre-installed 'opam'
 * Add 'seed' to system_tests_quick
(cherry picked from commit 000ffa7541252e1fa3b0e33ae5f72c7bb1837917)

Conflicts:
	jenkins/archive_version.sh
	jenkins/build_in_shandbox.sh
	jenkins/system_tests_quick/030_prepare_system_tests.sh
Jenkins: Set up 'system_tests_slow_left' job for LXC-based execution

 * Remove 'install sandbox' step from system_tests_slow_left
 * Add interpreter lines to system_tests_slow_left scripts
 * Remove 'sudo' usage from system_tests_slow_left
 * Add 'seed' file to system_tests_slow_left
(cherry picked from commit 38f6cd3ca12bb6025d0a1de5e5c28588a913bc9b)
Jenkins: Set up 'system_tests_slow_right' job for LXC-based execution

 * Remove 'install sandbox' step from system_tests_slow_right
 * Add interpreter lines to system_tests_slow_right scripts
 * Remove 'sudo' usage from system_tests_slow_right
 * sudo'ify 'iptables' calls in system_tests_slow_right
 * Add 'seed' file to system_tests_slow_right
(cherry picked from commit 44109e38877c85c7596eea6a1ad75519bf2ef06e)
Jenkins: Enable coverage reporting

See: 17734cecdd95ad8787b6ea7fb1bcd8ef04738279
(cherry picked from commit e456fbde35554848f18528f1ae1992cb1845fcd8)
Jenkins: Actually run profile build

See: e456fbde35554848f18528f1ae1992cb1845fcd8
(cherry picked from commit 5e8236c24e39d6ae3aaccf8048261af89ffec8b5)
Jenkins: Remove 'publish docs' step from 'base'

This should not be done as part of regular builds, only when releasing.
(cherry picked from commit 3d45ca5da06470eb28624b111e78e3d5f1793c53)
CI: tweaking jenkins scripts
(cherry picked from commit 42bfb3083026fa5d0cacd2ef1a5833cf6aa49016)

Conflicts:
	jenkins/build_in_shandbox.sh
	jenkins/system_tests_quick/030_prepare_system_tests.sh
CI: jenkins ...
(cherry picked from commit 182e28887a89e26f16f0854dfb28c4125a7addbc)

Conflicts:
	jenkins/system_tests_quick/030_prepare_system_tests.sh
adding qbase-extra
(cherry picked from commit 20bd2f193fde399968d99ea943b9e14a8f3bfec8)