Add support for enabling apache modules in PHP platform

Partially fix https://github.com/globocom/tsuru/issues/685
Fix https://github.com/globocom/tsuru/issues/682
Fix https://github.com/globocom/tsuru/issues/688

But introduce 1 bug:
 - output from "deploy" script is not wrote sequentilly, for example:

    remote: Hello world!
    remote: 
    remote: 
    remote: 
    remote: ========================================
    remote:  Parsing Hooks
    remote: ========================================
    remote: 
    remote:    Running hook: echo "Hello world!"
    remote:    Done executing hooks.
    remote:  * Restarting web server apache2
    remote:    ...done.
    remote: 
    remote: 
    remote: 
    remote: ========================================
    remote:  Parsing Apache modules to enable
    remote: ========================================
    remote: 
    remote:    Installing Apache module rewrite
    remote:    Done enabling Apache modules.


"Hello word" is an hook, defined in app.yaml:

    $ cat app.yaml 
    apache:
       modules:
          - rewrite
    
    hooks:
       build:
          - echo "Hello world!"

and it should be run after line

remote:  Parsing Hooks

defined inside hook.py and not at the first output line

    remote:  * Restarting web server apache2

is a restart done by apache_modules.py and should be wrote after 

    remote:  Parsing Apache modules to enable