Paypal deprecated name field fix.

**Problem**
Sending FirstName/LastName fields as well as the Name field was causing the last name to be entered twice. (See #593)

**Changes**
- Removes the Name field from Address tag (it is deprecated - including FirstName and LastName in the PayerName tag is enough)
- Use Signature validation instead of Certificate validation in the remote tests (They were the only credentials I had, plus Paypal recommends using Signature over Certificate)
- Update some calls to deprecated methods in the remote tests that were causing a bunch of warnings.

**Reviewers**
@jduff 
@BlakeMesdag