Adds tests to ensure that all pre-1.0 package versions are locked

Let me know if the tests should be more thorough. I'm not checking for ranges, just for the use of `^` or `~`, but that seems to be how we specify all dependencies in ember-cli.
I think we should avoid recreating the regexp's in `semver` package (which we already have as a dep).

The test might look like:

```javascript
var semver = require('semver');

assert(semver.gtr('1.0.0', deps[name]), '"' + name + '" has a valid version');
```