Add command-line flags. (refs #2463)
Merge branch '2449-keep-write-blocks' into 2449-keep-flags

Conflicts:
	services/keep/keep.go
Merge branch '2449-keep-write-blocks' into 2449-keep-flags
Merge branch 'master' into 2449-keep-flags
Updating docs for code review (refs #2463)
Update documentation for command-line flags (closes #2463, closes #2591).