Support for elixir function

[satchinjoshi]

Changes:

• [x] Adds the support for elixir function
• [x] Updated the readme

Since ruby and elixir has similar syntax I have just copied from ruby/cfi.vim and renamed few things. Seems to be working with all variation of the function.

  def greet(%{age: age}) when 6 < age and age < 12, do: "Hiya"
  def greet(%{age: age}) when 12 < age and age < 18, do: "Whatever"
  def greet(%{age: age}) when 60 < age, do: "You kids get off my lawn"
  def greet(_), do: "Hello"
  def greet do
    "Hello"
  end

[tyru]

Thanks!