Extend the WSDLReader implementation to allow reading of authenticated WSDLs

The WSDLImportWizardManager class is responsible for the SOAP-relational import routine. At various points in the import process, it is required to read the WSDL designated by the chosen connection profile.

There are 3 different implementations of reading the WSDL.
1) Using the URLHelper class (used in the WSDL connection profile wizards);
2) Using the wsdl4j library to return the initial definition;
3) Using the eclipse wst library to find all the imported schemas.

While 1) is being fixed in #TEIDDES-1334, 2) and 3) also require modification in order to allow the securityType/username/password to be passed in when these implementations load the WSDL from its URI.

Failure to pass in the credentials results in a 401 error (access denied) for authenticated WSDLs.