[feature/revisions] Not enabled after install, don't enable for update either

When fresh installing a board, the migrations aren't run; instead the schema
data file is run. In that file, post revision tracking is set to 0 by default
whereas the the migration was set to 1 by default. So that means boards being
updated would have this feature enabled by default but freshly installed
boards would have this feature disabeld by deafult.

PHPBB3-10755