Add configuration generation tool, update readme.

lib/mix/tasks/generate_config.ex

@@ -0,0 +1,17 @@
+defmodule Mix.Tasks.GenerateConfig do
+  use Mix.Task
+
+  @shortdoc "Generates a new config"
+  def run(_) do
+    IO.puts("Answer a few questions to generate a new config\n")
+    IO.puts("--- THIS WILL OVERWRITE YOUR config/generated_config.exs! ---\n")
+    domain = IO.gets("What is your domain name? (e.g. pleroma.soykaf.com): ") |> String.trim
+    name = IO.gets("What is the name of your instance? (e.g. Pleroma/Soykaf): ") |> String.trim
+    email = IO.gets("What's your admin email address: ") |> String.trim
+    secret =  :crypto.strong_rand_bytes(64) |> Base.encode64 |> binary_part(0, 64)
+
+    result = EEx.eval_file("lib/mix/tasks/sample_config.eex", [domain: domain, email: email, name: name, secret: secret])
+    IO.puts("\nWriting config to config/generated_config.exs.\n\nCheck it and configure your database, then copy it to either config/dev.secret.exs or config/prod.secret.exs")
+    File.write("config/generated_config.exs", result)
+  end
+end

lib/mix/tasks/sample_config.eex

@@ -0,0 +1,20 @@
+use Mix.Config
+
+config :pleroma, Pleroma.Web.Endpoint,
+   url: [host: "<%= domain %>", scheme: "https", port: 443],
+   secret_key_base: "<%= secret %>"
+
+config :pleroma, :instance,
+  name: "<%= name %>",
+  email: "<%= email %>",
+  limit: 5000,
+  registrations_open: true
+
+# Configure your database
+config :pleroma, Pleroma.Repo,
+  adapter: Ecto.Adapters.Postgres,
+  username: "postgres",
+  password: "postgres",
+  database: "pleroma_dev",
+  hostname: "localhost",
+  pool_size: 10