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/apps/commands

@@ -2,6 +2,7 @@
 [[ " apps apps:create apps:destroy help apps:help " == *" $1 "* ]] || exit $DOKKU_NOT_IMPLEMENTED_EXIT
 set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+source "$PLUGIN_AVAILABLE_PATH/apps/functions"
 
 case "$1" in
   apps)
@@ -10,12 +11,7 @@ case "$1" in
     ;;
 
   apps:create)
-    [[ -z $2 ]] && dokku_log_fail "Please specify an app to run the command on"
-    [[ -d "$DOKKU_ROOT/$2" ]] && dokku_log_fail "Name is already taken"
-    APP="$2"
-
-    mkdir -p "$DOKKU_ROOT/$APP"
-    echo "Creating $APP... done"
+    apps_create $2
     ;;
 
   apps:destroy)

plugins/apps/functions

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+
+apps_create() {
+  [[ -z $1 ]] && dokku_log_fail "Please specify an app to run the command on"
+  [[ -d "$DOKKU_ROOT/$1" ]] && dokku_log_fail "Name is already taken"
+  local APP="$1"
+
+  mkdir -p "$DOKKU_ROOT/$APP"
+  echo "Creating $APP... done"
+  plugn trigger post-create $APP
+}