Bump debian directory

This commit includes:
* bump debhelper and standards version to current,
* bump Python dependency to 2.7 (it's the default Python version
  in Debian stable; only ever going up from here),
* machine-readable copyright (DEP5),
* replaced rules script with simpler *.install files,
* renamed etc/init.d/live-installer -> debian/live-installer.init,
* removing postinst/postrm (all that was present before is already
  handled automatically with dh_* or dpkg triggers).
Better debug and exception handling

With this commit:
* `--debug` switch now sets Python's `__debug__ = True` (and
  the lack of it enables `-OO` optimizations),
* ˙sys.excepthook˙ (default exception handler) is replaced by a
  function that first prints a normal traceback, and then issues
  Python debugger if `__debug__` is `True`, so the programmer can
  interactively inspect their error,
* a couple of really pointless try-except blocks,

  ```
  try:
      ...
  except Exception, e:
      print e
  ```
  have been unindented, with potential programmers' errors handled
  by said excepthook. Additionally, the unindented blocks hold the
  following changes:
  * stripped of all trailing whitespace,
  * gtk.gdk.threads_enter/leave() calls have been replaced by
    gtk.gdk.lock context guard.
Print locals() before entering pdb
HACK: Fix gettext line so that installer runs
Use __debug__ variable to check if --debug
Added flags for cw and ss
Merge pull request #35 from kernc/better_debug

Better debug and exception handling
Merge pull request #38 from kernc/bump_debian

Bumped debian directory
Stop tracking ConfigObj and instead rely on Debian's

Also parses distribution name and version from /etc/os-release,
/etc/lsb-release, or, if those files are unavailable for some odd
reason, our (slightly moved) config, as appropriate.