Move some non-themed icons to pixmaps/ directory

* Add PIXMAP_PATH to constants
* Add PIXMAP_PATH to icon search path in Functions.py
* Add data/icons/pixmaps/ directory
* Move some icons to $datadir/pixmaps/blueman/
* Add pixmaps stuff to configure.ac
trivial: s,_Exit,Exit, in ExitItem.py

I think this was supposed to be relevant to translations, but
the underscore ("_") shows up in the UI text, so it's incorrect.
Merge pull request #135 from rworkman/trivial

trivial: s,_Exit,Exit, in ExitItem.py
Merge pull request #132 from rworkman/pixmap_move-review

Move some non-themed icons to pixmaps/ directory

I'm fine with things as is, you can file another pull if you want to adjust this in the future
Drop Custom Icon Option From StatusIcon Plugin

* No More Custom Icons Option
* Functions.py had a typo in Button Label
Update CHANGELOG.md
Remove HAL support - it's obsolete these days