rename .gbs.conf to gbs.conf.bak temporarily

There was a build failure issue with the latest gbs (0.24.9).
I found removing .gbs.conf will fix the issue.
Also, modifying upstream_branch's value "upstream" to
"origin/upstream" or "origin/tizen" etc will fix it, too.

I don't know which way is correct way to fix this issue.
To keep history of this file, I just rename it.
So, you can use gbs 0.24.9 to build the packages.

@tizen_fix

Change-Id: I1f84fcc596be72c820083e9be8587d2edb63848a

diff --git a/.gbs.conf b/gbs.conf.bak
similarity index 100%
rename from .gbs.conf
rename to gbs.conf.bak