(bug 43959) Add ability to reset certain option kinds in API.

Added the "resetkinds" option to action=options, so that when the
"reset" option is set, the user can control which kinds of options
are reset, rather than having to do all or none.

Also added documentation to the "change" parameter, since passing
it option keys without any "=value" after it will result in resetting
that specific option to its default value.

Change-Id: Id5bc1fffa0d487c0f152b79115205d2722f380d3
Merge "(bug 43959) Add ability to reset certain option kinds in API."