Ander Juaristi authored Jul 07, 2016 and Tim Rühsen committed Jul 08, 2016

* bootstrap.conf: add SKIP_PO=1, so that we don't have to pass
  the --skip-po flag every time we run bootstrap.
* README.md, contrib/check-hard, contrib/mingw, docs/mainpage.md,
  .travis.sh: amend references to autogen.sh.
* autogen.sh: Removed
* .gitignore: Add build-aux
* po/Makevars: Remove auto-generated file from repo