…r Linux. The target file is being highlighted, and "Show Extension Folder" (still) works.

For the highlighting to work, I had to detect the default file manager on the system, then run it with the target file as a parameter. If we failed to automatically determine the default file manager, the fallback behavior is to just open the directory containing the file (without the file being highlighted).
This is for https://trello.com/c/RF1ddQGK/898-linux-show-in-os-for-selected-file

Now using a IPC call to FileManager1, similar to what Firefox does.
The fallback remains the same. That is - call gtk_show_uri() on the file's parent directory (probably not needed, but just in case). Also, fixed the URI generation.

Also, updated the appshell.gyp file to include the new compilation/linking flags needed for the new function to compile properly.
The library "libdbus-glib-1-dev" is now a dependency, so it should be added to the wiki page.

The GLib library now includes its own DBus bindings, and so they recommend switching to the new bindings for new applications.
This requires glib-2.0 version at least 2.26 (at the moment of writing the latest version is 2.40).
Removed the dependency of the binding library (libdbus-glib-1), updated appshell.gyp accordingly.