fix bash shebang
add build caching
first pass at a decent user interface

This makes it somewhat easy to use.  From the root git dir, just:

  sudo scripts/kpatch-build ~/foo.patch

and it'll take care of everything, eventually spitting out the base
module (kpatch.ko) and the hotpatch module kpatch-foo.ko.

This is still all very crude, but a better user interface is coming
soon.
functional reorganization

Organize the files functionally:
- kmod/core: core kmod source
- kmod/patch: patch kmod source
- kpatch: kpatch script
- kpatch-build: kpatch build script and supporting tools
- contrib: distro-related files
compressed cache

Saves about 2G disk space per kernel version
clarify that kpatch should work on non-Fedora
use consistent naming for core and patch modules
Merge pull request #4 from jpoimboe/usability

Interface improvements