document new default for pastish_user
README updated from pastish.1
susepaste.org capability documented
pastish -A <api> selects code path, configuration

supported values for <api> are "ext" and "int".  pastish uses
the value of $pastish_server_<api>.  "ext" tunes the curl(1) calls
to the susepaste.org interface, "int" is for pastebin.suse.de.