Don't print anything to STDOUT during ACL granting

When run under the web installer, output to STDOUT is displayed in the
browser.  This led to "Granting access to ..." being displayed atop the
menu during the database initialization step.

MySQL is the only database type whose ACL tries to display output when
successful. As 'rt-setup-database' provides sufficient updates as to
what is going on, an the specific GRANT being run is mostly irrelevant,
omit the warning entirely.  Switch to using the existing logging
infrastructure for the true warnings.
Ensure that all classes (and thus roles) are loaded prior to bootstrap

Bootstrapping involves creating some global role groups.  However, role
group creation now checks the metadata on which roles are allowed on
which objects.  As the core RT classes have not been loaded,
RT::System->Roles is empty, so creation of global role groups fails with
"ERROR: Invalid Group Name and Domain"

Load RT classes prior to inserting bootstrapping data, to ensure that
all roles are known.  t/web/install.t and t/web/installer.t did not
catch this failure because they both fork a Plack server, which inherits
all of the already-loaded modules from RT::Test -- and as such, all
roles had always already been loaded.
Merge branch '4.2/web-installer' into 4.2-trunk