Revert "Add null and emptystring tests to check NOT NULL"

This reverts commit c74f3d0b90.

tests/lib/appconfig.php

@@ -86,20 +86,6 @@ class Test_Appconfig extends PHPUnit_Framework_TestCase {
 		$this->assertEquals('somevalue', $value['configvalue']);
 	}
 
-	/**
-	 * @expectedException \Doctrine\DBAL\DBALException
-	*/
-	public function testSetValueNull() {
-		\OC_Appconfig::setValue('testapp', 'installed_version', null);
-	}
-
-	/**
-	 * @expectedException \Doctrine\DBAL\DBALException
-	*/
-	public function testSetValueEmptyString() {
-		\OC_Appconfig::setValue('testapp', '', '1.33.7');
-	}
-
 	public function testDeleteKey() {
 		\OC_Appconfig::deleteKey('testapp', 'deletethis');
 		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*appconfig` WHERE `appid` = ? AND `configkey` = ?');