Deprecate swift3, use s3api in Swift repo

swift3 is no longer actively maintained in the upstream.
That has been moved to Swift repository as s3api so we should
use s3api middleware instead. As well as swift3, s3token is
also maintained in Swift upstream.

Change-Id: I4582d81da066ab53e6f11ad1df7af91425f2b0ca
diff --git a/stack.sh b/stack.sh
index 4f6e5b6..cebd959 100755
--- a/stack.sh
+++ b/stack.sh
@@ -889,12 +889,10 @@
     stack_install_service swift
     configure_swift
 
-    # swift3 middleware to provide S3 emulation to Swift
-    if is_service_enabled swift3; then
+    # s3api middleware to provide S3 emulation to Swift
+    if is_service_enabled s3api; then
         # Replace the nova-objectstore port by the swift port
         S3_SERVICE_PORT=8080
-        git_clone $SWIFT3_REPO $SWIFT3_DIR $SWIFT3_BRANCH
-        setup_develop $SWIFT3_DIR
     fi
 fi