Move X cookie generation out of Session code.
Do not generate an cookie as root when loading

It's not used by anything
Remove explicit delete call to parented object

d->socket has the GreeterProxy object as a parent so will be deleted
anyway
Proxy messages from the greeter in SDDM output
Catch errors launching the greeter before we block.
Move generateName to a separate file
SocketServer generates it's own name

SocketServer is in charge of creating the socket name. It then exposes
the full socket path.

SocketServer is changed to not have m_started and the server in separate
states.
Only set session environment user/path if set
Start the greeter under the user sddm
Merge pull request #159 from davidedmundson/nonrootgreeter

Don't run the greeter as root
Set use rpath
Quote all CMake path arguments

Fixes #111
Use sddm.service as a file name in the source
Fix the CMake systemd regex
Merge pull request #176 from davidedmundson/rpath

Set use rpath
Merge pull request #175 from jleclanche/master

CMake quoting
Add instructions to readme
Merge pull request #177 from davidedmundson/readme

Add instructions to readme