Fix bug that produced duplicate ids on methods

in cases where methods are repeated due to being
in repeated resource_types.
Note that there are edge cases that this fix still
does not catch. For example, if the original
<wadl:resource> lacks an @id attribute, there
could be duplicate method ids pulled in via
resource_types.
Merge pull request #91 from dwcramer/fixDuplicateIds

Fix bug that produced duplicate ids on methods