Bugfix ubuntu release upgrader

There were multiple issues:
 - Sed tries to change symbolic links not owned by the user
 - Some packages were removed. This isn't needed when using trisquel chroots, as those packages are never avaliable.
 - The package used one file from ubuntu-drivers-common related to non-free nvidia drivers, that is not needed in trisquel. The source file can be found [here](http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/utopic/ubuntu-drivers-common/utopic-proposed/view/head:/share/obsolete)

See merge request !10

V2 helpers as user

See merge request !7

5 v2 crontab2english under artistic

Fix leny2010/package-helpers#5 for GNU FSDG bug report 10868

See merge request !11

As per leny2010/package-helpers#5

It wasn't a build-dep, and the only contents were packages not avaliable in trisquel.

Feature wxmaxima

Backported wxmaxima from ubuntu 14.10

Fixes #12785

See merge request !8

1 v4 allow ckermit into belenos

A rework of !3 to ensure the old commits are dropped.  That was simply me starting the weekend without either getting an update from @aklis or doing a long paperchase through the repos.

As per !3 i.e.

As per leny2010/package-helpers#1 ckermit has been free for some time. It has now percolated down to Multiverse in Trusty. Here is the package helper to bring it in.

I suggest you close !3 rejected

See merge request !4

Fixes #12785

Fix helper for firefox 34

See merge request !2