About configuration files for the user session

[Dmitrijs Ledkovs]

To summarise we are settling in for the following paths:
--confdir DIR option on the command line
${XDG_CONFIG_HOME:${HOME}/.config}/upstart
${HOME}/.init
${XDG_CONFIG_DIRS:/etc/xdg/}/upstart
/usr/share/upstart/session/

The last one is intended for packages to ship their job files such
that they don't have to be conf(ig) files.

Unless, the job file requires to call something [1] in the multiarch
paths. In that case you have a few options:
* figure out multi-arch paths in pre-start script
* ship the job file as a conf(ig) file in /etc/xdg/upstart with
multiarch paths embedded

Or if there are more usecases for mutliarch-aware paths we can, in the
future, add /usr/lib/$(multi-arch)/upstart/session/ .... but I don't
want to add those just yet.

[1] /etc/xdg/autostart/deja-dup-monitor.desktop calls
/usr/lib/x86_64-linux-gnu/deja-dup/deja-dup-monitor . The easy
solution is to simply ship deja-dup-monitor in /usr/bin/. Or as the
README file in deja-dup sources suggests convert the deja-dup-monitor
into multiple upstart jobs as appropriate.

Regards,

Dmitrijs.