Fix zephir generate View error

Error: Zephir\CompilerException: Cannot read variable 'cache_mode'
because it wasn't declared in
/home/vagrant/cphalcon-2.x.x/phalcon/mvc/view.zep on line 608
Fix zephir Generate libmemcached errors

Error: Zephir\CompilerException: Variable 'servers' cannot be read
because it's not initialized in
/home/vagrant/cphalcon-2.x.x/phalcon/session/adapter/libmemcached.zep on
line 87
Implement functions in \Phalcon\Mvc\Dispatcher class.

- Dispatcher->getPreviousControllerName();
- Dispatcher->getPreviousActionName();

Required by unit-test\DispatcherMvcTest.php on line 194 & 197

I "copied" code from cphalcon-1.3.1

Methodology:
- set variables in \Phalcon\Dispatcher->forward function
- implements getters in \Phalcon\Mvc\Dispatcher
Merge pull request #2507 from alkana/2.0.0

2.0.0 - Fix zephir Generate errors