Fix tests failing due to non-existent SOAP endpoints

[dhmlau]

Currently, our tests use http://www.webservicex.net/periodictable.asmx?WSDL and possibly other web services from webservicex.net that no longer exist. They should be updated to use valid URLs.

Tests in https://github.com/strongloop/loopback-connector-soap have been updated. Can use this as a reference.

Acceptance Criteria

• fix tests to use an endpoint that exists so that CI can pass again
  • can use https://github.com/strongloop/loopback-connector-soap/blob/master/test/test.js as a reference

[dhmlau]

Closing as resolved.