Update FormerlyVariable.php

Making displaying the submissions work. (Issue enigmadigital#16 and enigmadigital#46)

Example twig tags:
{# get latest submission values #}
{% set submissions = craft.formerly.submissions.get() %}
{% set submission = submissions.contactForm_email(':notempty:')[0] %}

variables/FormerlyVariable.php

@@ -16,6 +16,11 @@ public function form($handle)
 		return craft()->formerly_forms->getFormByHandle($handle);
 	}
 
+	public function submissions()
+	{
+		return craft()->elements->getCriteria('Formerly_Submission');
+	}
+
 	public function __get($prop)
 	{
 		if ($prop == 'submissions')