Merge remote-tracking branch 'remotes/ehabkost/tags/python-next-pull-request' into staging

Python queue, 2019-01-17

Fixes:
* Actually test different Python versions on Travis CI
* Fix qemu.py error message when qemu dies from signal

Cleanups:
* Track Python version on config-host.mak
* Remove fixed crashes from scripts/device-crash-test
* Acceptance tests: Linux initrd checking test
* Fix utf-8 mangling at scripts/replay-dump.py
* Remove unused python imports from multiple scripts

# gpg: Signature made Thu 17 Jan 2019 20:16:41 GMT
# gpg:                using RSA key 2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>"
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/python-next-pull-request:
  scripts/replay-dump.py: fix utf-8 mangling
  qemu.py: Fix error message when qemu dies from signal
  Acceptance tests: add Linux initrd checking test
  check-help: visual and content improvements
  Travis CI: make specified Python versions usable on jobs
  check-venv: use recorded Python version
  configure: keep track of Python version
  scripts: Remove unused python imports
  scripts/device-crash-test: Remove known crashes

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>