Fix to correct launching applications that are not currently installed on Steam.

Before, a recursion error would occur when trying to find the game path.
With the fix, Steam will launch and it will bring up the
installer window for the application.
Merge remote-tracking branch 'upstream/master'.
Fixed issue with system level configurations not being overridden in runners. Fixed error with subprocess.Popen when no cwd is specified.

The issue with system_config made it so that winesteam would never
be counted as being installed. I also noticed resolution selection
problems with the steam runner.
Use WINEPREFIX and wine path when performing regedit calls. Otherwise, regedit affects system level wine config files.

If a WINEPREFIX is specified, Lutris should make Wine configuration
changes in the prefix. If it doesn't, values specified in the runner
config will not be used. Also, Lutris should use the specified
wine executable in the runner config instead of wine installed
at the system level.
Merge remote-tracking branch 'upstream/master' into fixes.
Added changes to wine runner. command generation has been fixed for stop method. Allow custom wineboot path to be defined for create_prefix.
Covers the case when there is no system.yml file found.
Stricter check for steam linux executable in running processes.

Needed on SteamOS since system.get_pid keeps finding the
pid of the steamos-update script. This could cause Steam
for Windows to not launch as long as steamos-update
is running.
This is how system_config is supposed to work
Remove useless winesteam init and rename settings to config
Add base test for AddGameDialog
Return when SteamApps not found
Test get_list_store
Misconception about how system.yml is written
Separate test and cover tasks
One more system config test
get rid of LutrisConfig.get_system
Store steam location in winesteam runner config
Make steam_path visible from config dialog
Handle case where winesteam.yml does not exists