Added: ability to run tests via EVM

Hi!

This commit adds ability to run tests via EVM. It's assumes that you already have installed EVM and appropriate version of Emacs (via `evm install`).

Usage:

```sh
$ ./run_tests                # run tests with default emacs
$ ./run_tests emacs-24.3-bin # run tests with emacs version 24.3-bin
```

Ref #109