Vendorize ZF1, fix PHPUnit and configure travis

This a a rather large commit due to the nature of the stuff it is touching. To get PHPUnit up and running again I had to update some deps and I did so by vendorizing them. The vendorizing of zf1 makes sense since distros are already considering to drop it from their repos.

* [x] install vendorized zf1 with composer
* [x] load composer autoloader before zf1
* [x] Implement headAction for all Zend_Rest_Controller based controllers
* [x] switch to yml dataset to get around string only limitations of xml sets (also removed warning in readme)
* [x] use year 2044 as hardcoded date for tests since it is in the future and has the same days like previously used 2016
* [x] make tests easier to run when accessing phpunit directly
* [x] clean up test helper to always use airtime.conf
* [x] switch test dbname to libretime_test
* [x] test db username password switched to libretime/libretime
* [x] install phpunit with composer in a clear version (make tests easier to reproduce on other platforms)
* [x] remove local libs from airtime repo (most of airtime_mvc/library was not needed of in vendor already)
* [x] configure composer autoloading and use it (also removed requires that are not needed anymore)
* [x] add LibreTime prefix for FileNotFoundException (phing had a similar class and these are all pre-namespace style)
* [x] add .travis.yml file
* [x] make etc and logdir configurable with LIBRETIME_CONF_DIR and LIBRETIME_LOG_DIR env (so travis can change it)
* [x] slight cleanup in config for travis not to fail
* [x] add cloud_storage.conf for during test runs
* [x] rewrite mvc testing docs and move them to docs/ folder
* [x] don't use `static::class` in a class that does not have a parent class, use `__CLASS__` instead.
* [x] don't use `<ClassName>::class`, since we already know what class we want `"<ClassName>"` ist just fine.
* [x] fix "can't use method in write context" errors on 5.4 (also helps the optimizer)
* [x] add build status badge on main README.md

Fixes https://github.com/LibreTime/libretime/issues/4

The PHP parts of https://github.com/LibreTime/libretime/pull/10 get obsoleted by this change and it will need rebasing.

This also contains https://github.com/LibreTime/libretime/pull/8, the late static binding compat code was broken for no reason and until CentOS drops php 5.4 there is no reason I'm aware of not to support it. I inlined #8 since the test would be failing on php 5.4 without the change.

If you want to run tests you need to run `composer install` in the root directory and then `cd airtime_mvc/tests && ../../vendor/bin/phpunit`. For the tests to run the user `libretime` needs to be allowed to create the `libretime_test` database. See `docs/TESTING.md` for more info on getting set up.

airtime_mvc/application/controllers/ShowbuilderController.php

@@ -1,7 +1,5 @@
 <?php
 
-require_once('CORSHelper.php');
-
 class ShowbuilderController extends Zend_Controller_Action
 {