Fixed broken compile with lowercase header parts

[jankeesvanandel]

Hey,

We use scalaxb and after upgrading to v1.4.1 things broke in the compile phase. This was the error:

[info] Compiling 11 Scala sources to /***/target/scala-2.11/classes...
[error] /***/target/scala-2.11/src_managed/main/sbt-scalaxb/***/wsdl/MyService.scala:9: getGroupProfileRequest is already defined as value getGroupProfileRequest

And this was the generated source file, causing the error:

trait MyService {
  def getGroupProfile(getGroupProfileRequest: ***.wsdl.GetGroupProfileRequest, authenticationHeader: ***.wsdl.AuthenticationHeader, getGroupProfileRequest: ***.wsdl.GetGroupProfileRequest, authenticationHeader: ***.wsdl.AuthenticationHeader): Future[***.wsdl.GetGroupProfileResponse]
}

As you can see, the header and body part arguments were added twice.

We found out that this was introduced in commit 8b2b20d, the reason being a lowerCase operation that was applied only on one place, causing Map lookup misses.

[eed3si9n]

Thanks for the contribution!