Remove unneeded unit tests

tests/data/testcal.ics

@@ -1,13 +0,0 @@
-BEGIN:VCALENDAR
-PRODID:-//some random cal software//EN
-VERSION:2.0
-BEGIN:VEVENT
-CREATED:20130102T120000Z
-LAST-MODIFIED:20130102T120000Z
-DTSTAMP:20130102T120000Z
-UID:f106ecdf-c716-43ef-9d94-4e6f19f2fcfb
-SUMMARY:a test cal file
-DTSTART;VALUE=DATE:20130101
-DTEND;VALUE=DATE:20130102
-END:VEVENT
-END:VCALENDAR

tests/data/testcontact.vcf

@@ -1,6 +0,0 @@
-BEGIN:VCARD
-VERSION:3.0
-PRODID:-//some random contact software//EN
-N:def;abc;;;
-FN:abc def
-END:VCARD

tests/lib/preview.php

@@ -97,13 +97,9 @@ class Preview extends \PHPUnit_Framework_TestCase {
 
 	public function txtBlacklist() {
 		$txt = 'random text file';
-		$ics = file_get_contents(__DIR__ . '/../data/testcal.ics');
-		$vcf = file_get_contents(__DIR__ . '/../data/testcontact.vcf');
 
 		return array(
 			array('txt', $txt, false),
-			array('ics', $ics, true),
-			array('vcf', $vcf, true),
 		);
 	}