(PUP-2901/PE-4524) Add module dependency validation

Prior to this commit there wasn't much verification for module dependencies.
This commit adds verification the module dependencies have sane names and version
ranges. If verification fails, it will raise an argument exception.
This occurs when there is any non-equal specification, even when they don't "conflict". Example:
```
cheddar:~/puppet/src/puppet (PE2838)$ bundle exec puppet module build anderson-no1
Error: Dependency conflict for : Dependency puppetlabs-stdlib was given conflicting version requirements >= 1.0.0 and >= 2.0.0. Verify that there are no duplicates in the metadata.json or the Modulefile.
Error: Try 'puppet help module build' for usage
```

@laurenrother gives alternative wording: 
Multiple dependencies specified: Multiple dependencies were given for puppetlabs-stdlib (>= 1.0.0 and >=2.0.0).
Please specify one version_requirement in the metadata.json.