Wagon fails to validate correct wagons

[mcouthon]

This is actually probably 2 issues.

Issue 1

Steps to reproduce:

• wagon create pip
• wagon validate <RESULTING_WAGON>
  The validation will fail.

Issue 2

The steps to reproduce are the same, but here the cause is clear - after pip install _s change to -s, and so this fails.
For example, here's a package on which create/validate will fail.

[nir0s]

@mcouthon well, that's actually a pip thing. Even when the package is named target_mock, the name when you run pip freeze will show target-mock.

What we can do, is one of two things:

1. Validate both _ and -.
2. Make sure the package name is always with dashes instead of underscores. I think this is a dangerous option (albeit more aesthetic), so I wouldn't go for it.

[mcouthon]

@nir0s Validating both seems sensible (and easy to implement).