Conform to function declaration standards

- declare desc variable
- declare all positional arguments
- set the cmd
- properly handle DOKKU_APP_NAME

subcommands/create

@@ -5,9 +5,13 @@ source "$PLUGIN_BASE_PATH/common/functions"
 source "$(dirname "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)")/functions"
 
 mongo-create-cmd() {
-  [[ -z $2 ]] && dokku_log_fail "Please specify a name for the service"
-  [[ ! -d "$PLUGIN_DATA_ROOT/$2" ]] || dokku_log_fail "$PLUGIN_SERVICE service $2 already exists"
-  SERVICE="$2"; SERVICE_ROOT="$PLUGIN_DATA_ROOT/$SERVICE"; LINKS_FILE="$SERVICE_ROOT/LINKS"
+  declare desc="create a $PLUGIN_SERVICE service"
+  local cmd="$PLUGIN_COMMAND_PREFIX:create" argv=("$@"); [[ ${argv[0]} == "$cmd" ]] && shift 1
+  declare SERVICE="$1"
+
+  [[ -z "$SERVICE" ]] && dokku_log_fail "Please specify a name for the service"
+  [[ ! -d "$PLUGIN_DATA_ROOT/$SERVICE" ]] || dokku_log_fail "$PLUGIN_SERVICE service $SERVICE already exists"
+  SERVICE_ROOT="$PLUGIN_DATA_ROOT/$SERVICE"; LINKS_FILE="$SERVICE_ROOT/LINKS"
 
   if ! docker images | grep -e "^$PLUGIN_IMAGE " | grep -q " $PLUGIN_IMAGE_VERSION " ; then
     docker pull "$PLUGIN_IMAGE:$PLUGIN_IMAGE_VERSION" || dokku_log_fail "$PLUGIN_SERVICE image $PLUGIN_IMAGE:$PLUGIN_IMAGE_VERSION pull failed"