add elixir 1.3 and 1.4 support back (#33)

* support elixir 1.3 and 1.4

* update elixir version requirement

* can not support elixir 1.3 via erlang 20

.travis.yml

 language: elixir
 matrix:
   include:
+    - os: linux
+      sudo: required
+      otp_release: 19.3
+      elixir: 1.3.4
+
+    - os: linux
+      sudo: required
+      otp_release: 19.3
+      elixir: 1.4.5
+
+    - os: linux
+      sudo: required
+      otp_release: 20.0
+      elixir: 1.4.5
+
+    - os: linux
+      sudo: required
+      otp_release: 19.3
+      elixir: 1.5.0
+
     - os: linux
       sudo: required
       otp_release: 20.0
       elixir: 1.5.0
+
 notifications:
   recipients:
     - self@falood.me

mix.exs

@@ -4,8 +4,7 @@ defmodule FileSystem.Mixfile do
   def project do
     [ app: :file_system,
       version: "0.1.1",
-      elixir: "~> 1.5",
-      compilers: [:elixir, :app],
+      elixir: "~> 1.3",
       deps: deps(),
       description: "A file system change watcher wrapper based on [fs](https://github.com/synrc/fs)",
       source_url: "https://github.com/falood/file_system",
@@ -19,7 +18,7 @@ defmodule FileSystem.Mixfile do
 
   def application do
     [
-      extra_applications: [:logger],
+      applications: [:logger],
     ]
   end