Properly quote variables

In general, we have to be more diligent in using variables, see http://tldp.org/LDP/abs/html/quotingvar.html.
Fix typo
Merge pull request #161 from iblech/patch-1

Fix missing quotes and a typo in the install script
KJ_NORETURN changed. Fix build.

Since we strictly use latest clang, I went ahead and used C++11-style attributes rather than the macro.
Merge branch 'master' of github.com:sandstorm-io/sandstorm