Init Elixir project

Starting fresh with...

```shell
mix new server
```

assessments/semiprimes/server/lib/server.ex

@@ -0,0 +1,18 @@
+defmodule Server do
+  @moduledoc """
+  Documentation for `Server`.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> Server.hello()
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end