Merge lp://qastaging/~mterry/indicator-session/snap-root into lp://qastaging/indicator-session

Work inside a snap by prefixing hard coded paths with $SNAP.

There are also two hardcoded paths in the data/*.desktop.in files. But that's a static desktop file, so $SNAP isn't appropriate.

I'm not sure what the best solution for those is, but presumably it would lie in whichever component consumes the desktop file, not this package.

And I left the "/usr/share/apport/recoverable_problem" hardcoded path in src/recoverable-problem.c. That seems like more of a deb-based reporting tool anyway. And I wasn't sure there is some plan for snappy to include an error reporting tool or what.