linaro-media-create speedup

[Tom Gall]

Greets,

As a side project I've created a fairly simple performance improvement
for the linaro-media-create tool. Basically the copying of the root_fs
happens earlier in the process such that hwpack and a number of other
steps are done in parallel and then at the end there's one last rsync
to make sure adjusted files, further installed files are correctly
copied.

The code is located here : lp:~tom-gall/linaro-image-tools/rsync-speedup

I'm still testing so use with caution.

>From what I've been able to accomplish thus far, the 67M
linaro-headless + hwpack sees the following speed up collected with
time:

Normal:
real	10m0.596s
user	2m2.670s
sys	0m9.820s

Parallel:
real	7m58.790s
user	2m3.170s
sys	0m11.950s


Feedback gladly accepted,

Regards,
Tom