Removal of migration scripts (both MATE and ubuntu one)

Accepting 1:0.9.12.1+15.04.20150213-0ubuntu1, but the migration script should be checked.

For reference, IRC discussion:
didrocks | Mirv: why is there this remove unity script on upgrade?
didrocks | Mirv: the default profile plugin doesn't use unity for mate
didrocks | (see debian/mate.ini)
didrocks | Mirv: all the rest is good, but this part should be clarified
didrocks | bregma: yeah, I see it's a copy of my own migration script a while ago, but this was to transition from "default" to "ubuntu" session (and so, leave the default session with compiz without unityshell)
didrocks | bregma: If I'm right and can still read my code, no promise :p
didrocks | bregma: yeah, it's not really a biggy but I feel it's not of use (and will just create a delay at startup), so better to check
didrocks | bregma: maybe you can even clear my old migration script, the LTS has passed :)
bregma | didrocks, would it be acceptable to promote the current MATE changes as-is and open a bug to remove all the migration stuff before Vivid release?