Tell users it's not our fault when no compatible versions are found

@domenic Fixes #3810

Example output: 

```
(18:08:03) [robert@tequila-osx] ~ $ npm i ./foo
npm http GET https://registry.npmjs.org/foo-private
npm http 304 https://registry.npmjs.org/foo-private
npm ERR! notarget No compatible version found: foo-private@'>=0.5.0-0 <0.6.0-0'
npm ERR! notarget Valid install targets:
npm ERR! notarget ["0.0.0","0.0.1","0.0.2","0.0.3","0.4.0","0.4.1","0.4.2"]
npm ERR! notarget
npm ERR! notarget This is most likely not a problem with npm itself.
npm ERR! notarget In most cases you are requesting a package version that
npm ERR! notarget doesn't exist.

npm ERR! System Darwin 12.5.0
npm ERR! command "node" "/Users/robert/.nvm/v0.10.21/bin/npm" "i" "./foo"
npm ERR! cwd /Users/robert
npm ERR! node -v v0.10.21
npm ERR! npm -v 1.3.13
npm ERR! code ETARGET
npm ERR!
npm ERR! Additional logging details can be found in:
npm ERR!     /Users/robert/npm-debug.log
npm ERR! not ok code 0
```