mix new creates 1 more extra file now (#1695)
mix new creates 1 more extra file now (#1695)

This is my output what mix creates right now

```
mix new example
* creating README.md
* creating .formatter.exs
* creating .gitignore
* creating mix.exs
* creating config
* creating config/config.exs
* creating lib
* creating lib/example.ex
* creating test
* creating test/test_helper.exs
* creating test/example_test.exs

Your Mix project was created successfully.
You can use "mix" to compile it, test it, and more:

    cd example
    mix test

Run "mix help" for more commands.
```

mix --version
Erlang/OTP 21 [erts-10.2.1] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe] [dtrace]

Mix 1.8.0 (compiled with Erlang/OTP 21)
nscyclone/elixir-school,doomspork/elixir_school,nscyclone/elixir-school,doomspork/elixir_school,doomspork/elixir-school,nscyclone/elixir-school,doomspork/elixir_school,doomspork/elixir-school,doomspork/elixir-school,nscyclone/elixir-school