Added permissions back to installation files

The scripts we provide should be executable by default. I went added and added the file permissions back wherever they were removed (c71da5621f505283ec85d37f7d2540a39b04d1ec). As far as I can tell, these permissions do not change the permissions of containing directories.

As far as the permissions we should actually be using go, I wouldn't mind some discussion. I think I mostly agree with what's here.