Refactor modules into contexts (#78)

* [WIP] break out a few contexts, start refactoring fast index modules

* [WIP] more contexts, this time around slow indexing and downloads

* [WIP] got all tests passing

* [WIP] Added moduledocs

* Built a genserver to rename old jobs on boot

* Added a module naming check; moved things around

* Fixed specs

lib/pinchflat/utils/filesystem_utils.ex

@@ -1,23 +0,0 @@
-defmodule Pinchflat.Utils.FilesystemUtils do
-  @moduledoc """
-  Utility methods for working with the filesystem
-  """
-
-  alias Pinchflat.Utils.StringUtils
-
-  @doc """
-  Generates a temporary file and returns its path. The file is empty and has the given type.
-  Generates all the directories in the path if they don't exist.
-
-  Returns binary()
-  """
-  def generate_metadata_tmpfile(type) do
-    tmpfile_directory = Application.get_env(:pinchflat, :tmpfile_directory)
-    filepath = Path.join([tmpfile_directory, "#{StringUtils.random_string(64)}.#{type}"])
-
-    :ok = File.mkdir_p!(Path.dirname(filepath))
-    :ok = File.write(filepath, "")
-
-    filepath
-  end
-end