Add post-create hook

Note that this is invoked *before* the application is deployed, so it's usage is quite different than a potential post-successful-create hook.

plugins/git/commands

@@ -1,6 +1,7 @@
 #!/usr/bin/env bash
 set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+source "$PLUGIN_AVAILABLE_PATH/apps/functions"
 
 git_build_app_repo() {
   verify_app_name "$1"
@@ -14,6 +15,7 @@ git_build_app_repo() {
   chmod 755 $TMP_WORK_DIR
   unset GIT_DIR GIT_WORK_TREE
   pushd $TMP_WORK_DIR > /dev/null
+  [[ ! -d "$DOKKU_ROOT/$APP" ]] && apps_create $APP
   git clone -q "$DOKKU_ROOT/$APP" "$TMP_WORK_DIR" &> /dev/null
   git config advice.detachedHead false
   git checkout "$REV" &> /dev/null