script/generate friendly_id doesn't make sure lib/tasks exist

[technicalpickles]

I was running the generator on a project I had cloned from git... and because git doesn't keep around empty directories, lib/tasks didn't exist. The generator failed because it was trying to copy friendly_id.rake into a directory that didn't exist yet.

To address this, the generator just needs to do m.directory "lib/tasks" before putting a file in there.

[technicalpickles]

This should be sufficient: 5960251

[norman]

I just applied your commit to the edge branch and will get it in the next release (along with your other recent patch). Thanks a lot for the help.