Drop support for Elixir 1.5

.travis.yml

@@ -1,8 +1,6 @@
 language: elixir
 matrix:
   include:
-    - otp_release: 20.0
-      elixir: 1.5
     - otp_release: 19.3
       elixir: 1.6
     - otp_release: 21.0

CHANGELOG.md

@@ -5,6 +5,15 @@ This project adheres to [Semantic Versioning](http://semver.org/) and
 [Keep a CHANGELOG](http://keepachangelog.com).
 
 
+## Unreleased
+
+No significant changes. Just some adoptions to work with RDF.ex 0.5, which drops
+support for Elixir versions < 1.6.
+
+[Compare v0.2.3...HEAD](https://github.com/marcelotto/jsonld-ex/compare/v0.2.3...HEAD)
+
+
+
 ## 0.2.3 - 2018-07-11
 
 - Upgrade to Jason 1.1

mix.exs

@@ -9,7 +9,7 @@ defmodule JSON.LD.Mixfile do
     [
       app: :json_ld,
       version: @version,
-      elixir: "~> 1.5",
+      elixir: "~> 1.6",
       build_embedded: Mix.env == :prod,
       start_permanent: Mix.env == :prod,
       deps: deps(),