(maint) Remove desc for generate tasks

The benchmark generate tasks are only for internal use by the other
tasks that users should use (run and profile). Putting a descritpion on
it, though, made it visible in `rake -T` and `rake -D`. This removes it
so that users aren't confused.
(PUP-1144) Improve handling of underscore in variable names

The last segment of a qualified variable name is allowed to start
with an underscore. Previously this was only allowed for a single
segment.
Merge pull request #2399 from hlindberg/pup-1144_underscore-in-last-segment

(PUP-1144) Improve handling of underscore in variable names
Merge branch 'master' of https://github.com/puppetlabs/puppet