Friendly error message when command is omitted.
Expose node's execPath to scripts

Re: einaros/ws#129
v1.1.66
read-package-json@0.1.9
minimatch@0.2.9
Prevent recursive installation on make
semver@1.1.1
node-gyp@0.7.3
read-package-json@0.1.10
npmconf@0.0.16
v1.1.67
read-package-json@0.1.11
v1.1.68
tar@0.1.14
Surround npm/node paths with quotes on Windows.

Allows tests to run there.
Stop trying to `spawn` non-exe's on Windows.
Don't "npm rm npm" on Windows.
Convert shrinkwrap test script from bash to Node.

Works better on Windows.
Docs: cli/registry - npm site now exists
Fix tests on unix