Cleaned up before_script.sh so that it was possible to reuse it for Vagrant

I have completely reworked the current `before_script.sh` so that it was possible to reuse it with `Vagrant`

At this moment the `Vagrant`-driven environment **completely** reproduces results on `travis-ci`

### How to use

    vagrant up
    # then it's recommended to increase RAM and CPUs (see the note below)

    vagrant ssh
    vendor/bin/phpunit Tests

### **IMPORTANT NOTE**
after `vagrant` has initialized the VM it makes sense to change amount of memory (and number of CPUs) manually from 384Mb by default to something near 2Gb (and 2 CPUs accordingly). Otherwise VM will swap hardly and at least one test will crash due to Out Of Memory.