Run test on drone

tryton has many tests scattered in its code.
It will be better to use the same design as other package and run tests on drone.

assigned to @ced

added tryton type::feature + 1 deleted label

Here are review258541002
And review282501004 which creates docker image for testing because tryton requires to have GTK and it will be too expensive to install it on each build (just like for sao).

added 1 deleted label and removed 1 deleted label

review258541002 updated at https://codereview.tryton.org/258541002/#ps272631002

review282501004 updated at https://codereview.tryton.org/282501004/#ps282521003

New changeset 849230d94ed2 by Cédric Krier in branch 'default':
Initial commit
https://hg.tryton.org/tryton-docker-tryton-test/rev/849230d94ed2

added 1 deleted label and removed 1 deleted label

closed

New changeset e032ae3f4015 by Cédric Krier in branch 'default':
Add unittest
https://hg.tryton.org/tryton/rev/e032ae3f4015

New changeset 754048c8c74f by Cédric Krier in branch 'default':
Remove assert from tests
https://hg.tryton.org/tryton-env/rev/754048c8c74f