add metapodfromurdf generator

and use it to generate the sample models.
metapodfromurdf: ensure compat with boost 1.40
Merge pull request #45 from sbarthelemy/add_metapodfromurdf1

Add metapodfromurdf to metapod (done)
fix metapodfromurdf error
Merge remote-tracking branch 'laas/master' into qibuild