allow 'systemd' ksmeta to be non-boolean

Bug: 1123700
Change-Id: Ie5e8dc6fda0c9cfcb1553493ce9e14d98893e855
only return watchdogs as 'expired' if all recipes in the set are expired

Bug: 1123249
Change-Id: I9c8e93637a852aaf2411df5a3a91abed9aaef87a
sort Table and Keyvalue dropdowns in search bar

Bug: 1120705
Change-Id: I7286c631bd40245b38451cda5069d9b444e7a4a3
fix <system_type/> injection in Recipe.host_requires

Bug: 1122659
Change-Id: I881fdffc02fbb48516f88cb329d221fdf4264bfb
release notes for 0.17.2

Change-Id: Ifeca30be49af9fcb97c6364d891d4e33ecccde8a
set 'systemd' variable before ks_meta

Bug: 1123700
Change-Id: Ia214575fd2ea34bfeb80f65bb460e12b79226538
Automatic commit of release 0.17.2