Remove useless things.
Add mock\generator::disallowUndefinedMethodInInterface().
Enable/disable restriction on undefined methods from config file

Related to #355 (https://github.com/atoum/atoum/pull/355#issuecomment-57480663)
Add mock\generator::disallowUndefinedMethodInInterface()

By default, it's possible to call a method undefined in a mocked interface.
However, in some case, it's a problem because you have no feedback if your tested code use an undefined method in an interface.
This is an example in pseudo-code:

<?php

interface foo
{
}

use mock\foo;

class bar extends \atoum
{
   function testSomething()
   {
      $this
         ->given($foo = new foo)
         ->if($this->newTestedInstance)
         ->then
            ->object($this->testedInstance->something($foo))->isTestedInstance
            ->mock($foo->call('undefinedMethod')->withIdenticalArguments($this->testedInstance)->once
      ;
   }
}

?>

When this code is executed, atoum generate no warning about the fact that foo::undefinedMethod() is not defined in foo interface, so the user can omit to add in it.
With this patch, the user will be notify by atoum in this case if the method disallowUndefinedMethodInInterface() is used:

<?php

class bar extends \atoum
{
   function testSomething()
   {
      $this
         ->mockGenerator->disallowUndefinedMethodInInterface()
         ->given($foo = new foo)
         ->if($this->newTestedInstance)
         ->then
	    ->object($this->testedInstance->something($foo))->isTestedInstance
	    ->mock($foo->call('undefinedMethod')->withIdenticalArguments($this->testedInstance)->once
      ;
   }
}

// Failure (1 test, 0/1 method, 0 void method, 0 skipped method, 1 uncompleted method, 0 failure, 1 error, 0 exception)!
// > There is 1 error:
// => bar::testSomething():
// ==> Error FATAL ERROR in /path/to/tests/units/bar.php on unknown line, generated by file /path/to/bar.php on line X:
// Call to undefined method mock\foo::undefinedMethod()

?>

This feature is available from a configuration file, thanks to @jubianchi.
Add mock\generator::disallowUndefinedMethodInInterface().