More clear error message on not having Erlang 17

I had this error, and I saw someone having it today,
which consists of not having Erlang 17 installed, and try to running Elixir:

```
ERROR: Failed to extract name from /Users/jayson/apps/elixir/lib/elixir/src/elixir.app.src: {11,
erl_parse,
["syntax error before: ",
"'{'"]}
make: *** [clean] Error 1
```

What about changing the warning to something more clear?
