guestroot.local: add .gitignore to ignore files under guestroot.local/.
vmbuilder.conf: add symlink to copy.txt generation target.
xexecscript.d: add 00_yum-conf.sh to disable "updates" repository.
guestroot: add everyboot hook.
box-ctl.sh: add raw2vdi task.
box-ctl.sh: add raw2vmdk task.
box-ctl.sh: add dist_raw/dist_vdi/dist_vmdk tasks. remove dist task.
add gen-image-size-params.sh.