ssh: fix fetcher

* set localpath in urldata_init
  otherwise localpath and basename were None, when fetcher was trying to
  define .lock and .done paths
  basepath = d.expand("${DL_DIR}/%s" % os.path.basename(self.localpath or self.basename))
* remove "host" from localpath
  .done and .lock files are always using just basename, so if someone
  has 2 recipes with:
  SRC_URI = "ssh://foo/file.txt"
  SRC_URI = "ssh://bar/file.txt"
  then there will be only one file.txt.done in downloads anyway (and
  only first file.txt from first server will be returned on do_fetch

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
ssh.py: throw ParameterError when someone tries ssh://foo; protocol=git

* taken from SFTP fetcher:
  http://patchwork.openembedded.org/patch/43027/

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
ssh.py: add example SRC_URI

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>