Fix building commands tree
Fix building commands tree

Find and load plugins before building the commands tree.
Actually it load plugins but it doesn't update the commands
tree, so plugins commands are not recognized.

Change-Id: Iddd4b4b887f70b26abc0068ad05b735d4c5ef5fb

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh