Fix plugin autoload

Autoload of some plugins fails because of mix between include paths
This commit remove the burden to include plugin autoload each and every time

Change-Id: Ib67247b47c9036b35ab2276bc7f0427b5f70eb48
Merge commit 'refs/changes/88/1388/2' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  Fix plugin autoload

Change-Id: I76163ab006f3c2038123b0fa6b1ef822a38e0a56
This is Tuleap 6.6.99.23

Change-Id: I652718dd63eda0b2aaa069f844d1d49151528efc