Constraint with wildcards

Was poking at using this for python version constraints, and it seems wild cards are not supported.

```
>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, != 3.4.*
```

It errors as follows:

```
Malformed constraint: !=3.0.*
```

No source files or tests are named in the issue. Start by reproducing the shown constraint parsing error, then trace the constraint parser and existing version-constraint tests; done means the wildcard exclusions in the example are accepted and covered by tests.

Written by the indexing model from the issue text.