A simple extension for SilverStripe 3.1 that restores the meta tag behavior of 3.0. Needs SiteTree::add_extension('MetadataExtension'); in your config.

MetadataExtension.php

class MetadataExtension extends DataExtension {

    static $db = array(
		'MetaTitle' => 'Varchar(255)',
		'MetaKeywords' => 'Varchar(1024)',
	);

	function updateCMSFields(FieldList $fields) {
		$metadata_field = $fields->fieldByName('Root.Main.Metadata');
		$metatitle_field = new TextField('MetaTitle', $this->owner->fieldLabel('MetaTitle'));
		$metakeywords_field = new TextareaField('MetaKeywords', $this->owner->fieldLabel('MetaKeywords'));
		$metatitle_field
				->setRightTitle(_t('SiteTree.METATITLEHELP',
					   'Replaces the page name in the HTML <title> element (requires template support).'))
				->addExtraClass('help');
		$metakeywords_field
				->setRightTitle(_t('SiteTree.METAKEYWORDSHELP',
					   'A list of keywords (not used by search engines; does not appear in HTML without template support).'))
				->addExtraClass('help');
		$metadata_field->push($metakeywords_field);
		$metadata_field->push($metatitle_field);
	}

}

Please let us know about this extension is fine https://gist.github.com/blpraveen/8c64f04f97cd43cbad3c