kiwi-build: Update to mimic production builds more closely

Production builds in Fedora have a couple extra features:

* ISOs have custom overrides to set the correct volume/app IDs
* Image filenames are structured to follow roughly NVRA format

Now we support these features with extra helper scripts. If a
"image release" value is passed in, then we fully mimic the
production image build process.

This will be particularly useful for making respins of Fedora images
with updates applied.

.gitignore

@@ -1 +1,2 @@
+outdir-build/
 outdir/