Use local git repositories

This commit adds a tocirc file that specifies a list of known working
git references to be used by d-i-b elements.

It also changes toci to use /opt/toci as a working directory only
recloning new repositories when their missing. This has a number of
advantages
1. building images from local cache should be faster
2. toci will not be efected by active repositories getting regressions
3. users can commit to local caches and try them out with triplo without
   having to edit elements to point to a fork
Remove unneed patches
Add exit to stop where we know works