Update to 1.13.8

Major changes in 1.13.8
=======================
* Added support for symbolic icons
* Removed favicon support
* Various build fixes and cleanup
* daemon: Return correct error for invalid backends
* daemon: Fix races when mounting the same mount in parallel
* daemon: Don't warn when running against an older gvfs-daemon
* gdbus: Don't g_warn about getting the dbus name
* gmountspec: Make sure to free the GVariantIter
* afc: Improve idevice error handling
* afc: Unpair an idevice if it was already paired and refuses to connect
* afc: Use the correct choice index for "Cancel"
* afp: fix g_vfs_afp_connection_get_max_request() not returning any value
* afp: Use human friendly error messages
* network: Don't set a file size for the network:// shortcuts
* network: Append the service name when needed to help differentiate
* recent: Honor the private hint
* Don't use the display name to make the unique mount point
* Don't include jargon in mount display names and messages
* Added more hints for translators
* Translation updates