guest-overlay: use squashfs and only pam mount

...les/provision/gast/.kde/share/config/libkcal_htmlexportrc

...lay/files/provision/gast/.kde/share/config/libkleopatrarc

...lay/files/provision/gast/.kde/share/config/mailtransports

...erlay/files/provision/gast/.kde/share/config/okularpartrc

...t-overlay/files/provision/gast/.kde/share/config/oxygenrc

...ay/files/provision/gast/.kde/share/config/phonondevicesrc

...provision/gast/.kde/share/config/plasma-desktop-appletsrc

...y/files/provision/gast/.kde/share/config/plasma-desktoprc

...rovision/gast/.kde/share/config/powermanagementprofilesrc

...t-overlay/files/provision/gast/.kde/share/config/sonnetrc

...provision/gast/.kde/share/config/specialmailcollectionsrc

...rlay/files/provision/gast/.kde/share/config/startupconfig

.../files/provision/gast/.kde/share/config/startupconfigkeys

...y/files/provision/gast/.kde/share/config/systemsettingsrc

guest-overlay/files/provision/gast/.kde/share/config/trashrc

...s/provision/gast/.local/share/contacts/WARNING_README.txt

.../.mozilla/firefox/Crash Reports/InstallTime20170419192459

...vision/gast/.mozilla/firefox/iokxbme1.default/.parentlock

...t/.mozilla/firefox/iokxbme1.default/AlternateServices.txt

...mozilla/firefox/iokxbme1.default/SecurityPreloadState.txt