Issue #2664322 by benjifisher, dawehner, daffie, almaudoh, mradcliffe, catch, quietone, alexpott, larowlan: key_value table is only used by a core service but it depends on system install

Revert "Issue #2664322 by dawehner, benjifisher, almaudoh: key_value table is only used by a core service but it depends on system install"

This reverts commit 5571193f.

Issue #2664322 by dawehner, benjifisher, almaudoh: key_value table is only used by a core service but it depends on system install

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #1547008 by Berdir, Sutharsan: Replace Update's cache system with the (expirable) key value store.

Issue #1642062 by tim.plunkett, xjm, chx, merlinofchaos, damiankloip, dawehner, Berdir, aspilicious, Fabianx: Add TempStore for persistent, limited-term storage of non-cache data.

Issue #1175054 by msonnabaum, chx, sun, tim.plunkett, arlinsandbulte, beejeebus: Add a storage (API) for persistent non-configuration state.