Added @InjectValue

Originally started by @vslinko (https://github.com/schmittjoh/JMSDiExtraBundle/pull/57)
Adds new annotation for injecting null or a string without using parameters into a service.

Usage:

        /**
         * @DI\InjectParams({
         *     "foo" = @DI\InjectValue(null),
         *     "bar" = @DI\InjectValue("baz")
         * })
         */
        public function leWildMethodAppears($foo, $bar)
        {
            // ...
        }