Swift3 1.7

Added a versin tag for distribution packages.

Likely Swift3 1.7 works with Swift 1.7.0 and the previous versions
however not with the following verions (1.7.1 and so on).

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Updated HEAD and ACL calls to objects to work correctly
Add basic support for multi object deletion

This adds basic support for deleting multiple objects from a bucket
using a single POST request.

TODOs:
 - support for deleting the specific version of the object.
 - return NoSuchBucked error when the specified bucket does not exist.
 - return MissingRequestBodyError error when the request body is
   empty.
 - return MalformedXML error when the provided XML is not well-formed.

Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
fix a bug for multi object deletion

This fix a bug for deleting multiple objects.
This change enables swift3 to receive request body
correctly in order to prevent that swift3 does not
return response for multi object deletion request.

Signed-off-by: Kota Tsuyuzaki <tsuyuzaki.kota@lab.ntt.co.jp>
Update README about keystone usage

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>