command: Use feed names in OPML 'text' attributes

command: Use feed names in OPML 'text' attributes

Instead of writing the URL as the 'text' attribute and ignoring it on
read, we now use the attribute to store the feed name.  This avoids
auto-generated feed names on import.  From the OPML 2.0 spec [1]:

  Subscription lists
  ...
  Required attributes: type, text, xmlUrl. For outline elements whose
  type is rss, the text attribute should initially be the top-level
  title element in the feed being pointed to, however since it is
  user-editable, processors should not depend on it always containing
  the title of the feed. xmlUrl is the http address of the feed.

We are not following the 'should' recommendation, but since we have
user-generated titles, I believe that the new usage is appropriate.
It's certainly closer to spec than storing a URL in 'text' :p.

[1]: http://dev.opml.org/spec2.html

Signed-off-by: W. Trevor King <wking@tremily.us>