Kill base::platform with fire

base::platform is currently a joke: it only acts on three minor server
models, one of which we don't own anymore; it sets up a $startup_devices
that is not used anywhere in our tree; and it sets up serial console
gettys using upstart, which Ubuntu automatically does anyway. Remove it
and its backreferences.

Change-Id: Iffe7a5eebdf3f93cc01b67fb9d1687bfde5a942e
Remove class base::packages::emacs

This class just installs the emacs23 package and is only included in one
place, role::statistics. Remove the base class, as it doesn't belong
there (and shouldn't have been a class anyway) and fold into
role::statistics (for now). Statistics really needs a revamp
(misc::statistics crap and all that), so hopefully it will get picked
up when that happens.

Change-Id: I8a2a571f73ae583cb66665058adbdbff2c183022