Fix infinite loop in get_file_device_path() in chroot environment #784.

In a chroot filesystem or if it didn't get the device for the file it will always treat it as a remotefs and cobbler will never try to create hard link in chroot filesystem.
add an option to always write DHCP entries regardless of netboot setting
Merge pull request #799 from santosh0705/chrootmtab

Fix infinite loop in get_file_device_path() in chroot environment #784.
Merge pull request #800 from aronparsons/always-write-dhcp-entries

add an option to always write DHCP entries regardless of netboot setting
Merge branch 'master' of https://github.com/cobbler/cobbler