Fix makefiles for various configurations

Just some small fixes to the makefiles, for compatibility with:
* the iOS 7.1 SDK
* Xcodes that aren't installed in `/Applications/Xcode.app` (e.g. beta copies)
* versions of `dpkg-deb` that don't compress with gzip by default and confuse the device, like the one installed from Homebrew.

Should be pretty self-explanatory. (Also, ignore the first two commits; they cancel each other out since the showAllIcons hook was added back in in 5fcf223…)

BTW: I'm also working on dynamically creating & destroying transform layers to hopefully fix #17 once and for all without all the glitchiness. It's on a feature branch, but at the moment it's a little too buggy and hacky for a merge.