Allow creation of reiser4 file systems on Linux 3.x (#742511)

With reiser4progs 1.0.7 and earlier mkfs specifically checks for Linux
kernel 2.5 or 2.6.  On Linux 3.x it fails with the following warning:

    # mkfs.reiser4 --yes --label "" /dev/sdb1
    Warn : Linux 3.13.0-39-generic is detected. Reiser4 does not support
    such a platform. Use -f to force over.
    # echo $?
    8

This is fixed in reiser4progs 1.0.8 and later.  From the reiser4progs
SourceForce README.txt:

    . Do not ask for confirmation to work under Linux-3.X;

Found on Ubuntu 12.04 LTS and Ubuntu 14.04 LTS both with reiser4progs
1.0.7 and a Linux 3.x kernel.

Fix by adding "--force" flag to the mkfs command line.

Bug 742511 - Creation of reiser4 file systems fails with unsupported
             warning