Filter transient duration

[plugin-republic]

Added a couple of filters for transient duration. Many gists are not updated regularly, if at all, so a longer transient duration can be used.

Example usage:

function pr_transient_expires( $duration ) {
  return MONTH_IN_SECONDS; 
}
add_filter( 'gistpress_transient_expire', 'pr_transient_expires' );
add_filter( 'gistpress_transient_expire_fallback', 'pr_transient_expires' );