README: Consistent capitalization of "GStreamer"

And consistent package naming (use the Fedora names, i.e.
"gstreamer-plugins-bad" instead of "gst-plugins-bad").
README: We no longer recommend using LIRC for recording test cases

Because configuring LIRC with 2 different hardware devices (one for
receiving and one for emitting) is complicated; see
http://stb-tester.com/multi-lirc.html

Instead we recommend using "stbt record --control-recorder=stbt-control"
extra/pylint.sh: Fix error triggered by certain outputs from pylint

If pylint's output contained a "%", you'd get an "invalid format
character" error from printf.
extra/stbt_checker.py: Fix import for pylint >= 1.0

IASTNGChecker was renamed to IAstroidChecker.

See: https://bitbucket.org/logilab/pylint/diff/interfaces.py?diff2=bdcbb695e59a&at=default

Note: I haven't found any mention of it on the official site,
found it on https://github.com/rory/python-pylint-i18n/pull/1 instead.

Thanks to Máté Szendro for the patch.
Remove extra/stbt_checker.py

Because it doesn't work with pylint 1.0. Running it against the python
script created by test_that_pylint_checker_ignores_generated_image_names
gives the following output:

    $ PYTHONPATH=stb-tester/extra/ \
        pylint --errors-only --load-plugins=stbt_checker test.py
    ************* Module test
    E:  4,26: Image ".png" not found on disk (None)
    E:  5,20: Image "%s.png" not found on disk (None)
    E:  6,46: Image "idontexist.png" not found on disk (None)

    $ echo $?
    2

So the checks done in `StbtChecker._is_calculated_value` aren't working.
I haven't investigated why, but I'm removing stbt_checker.py (added
recently in 8357f6b) because it's causing `make check` to fail on
systems with pylint 1.0, until I can fix it.
Fixes to (almost) pass `make-check` with pylint 1.0

pylint 1.0 still fails on stbt.py with "TypeError: unbound method
infer() must be called with Tuple instance as first argument" due to a
known bug, fixed in the as-yet unreleased pylint 1.0.1:
https://bitbucket.org/logilab/pylint/issue/47/

Other than that, I had to fix the following pylint violations resulting
from backwards-incompatible changes in pylint 1.0:

* The "REPORTS.output-format" configuration item is deprecated in favour
  of the equivalent "msg-template" configuration (this new configuration
  was suggested in the output-format deprecation warning that pylint
  printed).

* "^L", aka vertical tab, which is treated as whitespace by python and
  is used by Emacs as a section marker, now triggers pylint's "trailing
  whitespace" error. (This is probably fixed in the currently unreleased
  pylint 1.0.1: https://bitbucket.org/logilab/pylint/issue/55/ -- but
  I've removed the ^Ls anyway; they probably confused all the non Emacs
  users).

* Long lines inside docstrings now do trigger "line too long".

* Unused names starting with an underscore now trigger "unused
  variable". This is intentional; the release notes
  (http://www.logilab.org/blogentry/163292) say: "Do not treat all
  variables starting with "_" as dummy variables, only "_" itself.

* "C1001: Old-style class defined" is a new check introduced in pylint
  1.0.