Set XDG_CURRENT_DESKTOP for the started session

See https://git.reviewboard.kde.org/r/117400 for details
Fix UserModel.cpp to use getpwent()

Per open bug report #123

Also fix some problems with passwd struct argument
per comments from @aavci1
fix crash on double pam handle free

fixes sddm/sddm#145
Fix build deps
Search for user specific config path and merge with the default config

Better guard against null values in user config
If the user set background cannot be loaded fall back to the default one
Fix xauth annoying error
Add missing semicolon.
Don't set GDMSESSION as it is not used anymore.

Fixes #138.
improve .travis.yml

it's little bit messy, but it works
infrastructure is ready for clang, but for now build always fail
Added travis build status.
Open log only once and fallback to stdout when unable to open

Make QFile static to avoid opening and closing it for every log
message which will be rather slow.

Also, if it's not possible to open the log file fallback to
stdout to avoid losing log messages.
This is useful in test mode which runs as normal user.
Support logging to journald if enabled

Add support to journald logging that provides us much more information
such as code line and function, process command line, etc...
Logging works just like before when running interactively.

Since the DAEMON or GREETER prefix are not useful when logging to journald
and there was not even consistency between them, we now have two message
handlers respectively for daemon and greeter.

Those message handlers prepend the correct prefix to the message when
logging to file or stdout.  As a result all log messages don't need to
provide those prefixes anymore.
Flush stream when logging to standard output

Print everything in the stdout buffer immediately.
translate japanese
update JA translation
Add session information for logind

Make sure logind knows more information about the user session.
Make test mode parameter consistent and pass it to the greeter

Greeter now recognize --test-mode instead of --test for consistency,
also daemon pass this argument to the greeter if in test mode.
Remove debian subfolder
Fix some memory leaks if SDDM is closed when a session is running