Tests: Adjust diagnostic descriptions to match what's actually being tested
Tests: Correct a typo'd email address in the From: header
Tests: Catch the new "unparseable email address" warnings

A warning is now issued for each header field instead of a single
warning for all sender fields.
Tests: Remove Requestors from approval templates

The ->Requestors method returns an RT::Group object which stringified
during template interpolation.  The new email address parsing balks at
RT::Group=HASH(0xDEADBEEF), appropriately so.  Providing the actual
requestor email addresses would cause autoreplies to go out and the rest
of the test assumptions to break, so simply remove the requestors all
together.  Generally approval tickets don't use requestors in real use
cases anyway.
Tests: Catch warnings when calling DecodeMIMEWordsTo* without a field name

Or provide a field name when possible to avoid the warnings altogether.
We explicitly test without field names to compare results, but no where
in core RT should do the same.
Tests: Set a correspond address

... so we don't try to parse an empty address on the way back in.
Tests: Double quotes are not allowed by our email address parsing

The double quote case for requestor email addresses is skipped further
down in the file, but the ticket was still created with a bogus
requestor.  Avoid the added warnings by skipping the requestor when
testing double quotes.