The dash character (-) should be part of valid URIs.

I've been using the raml-jaxrs-codegen project and found an issue with the PathParam generation.

Let's say my RAML file has the following URIs:
```
/posts:
  /{post-id}:
```

In the generated interface, the method corresponding to the {post-id} will not contain a PathParam.

This issue stems from a class in the raml-java-parser project -- to be specific, the class "org.raml.parser.rule.BaseUriRule" and the "URI_PATTERN" regular expression.
w corresponds to ```[A-Za-z0-9_]```
but this does not include the character -

The URI_PATTERN regular expression is used in the class "org.raml.parser.visitor.RamlDocumentBuilder" to parse out the Uri Parameters.