Add erlang OTP 19 and Elixir 1.3.1 packages

packages/elixir.rb

+require 'package'
+
+class Elixir < Package
+  version '1.3.1'
+  depends_on 'erlang'
+
+  source_url 'https://github.com/elixir-lang/elixir/archive/v1.3.1.tar.gz'
+  source_sha1 '29dc1b4da5e051ad71ad84b6886d7c184e4b9add'
+
+  def self.build
+    system 'make clean test'
+  end
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end

packages/erlang.rb

+require 'package'
+
+class Erlang < Package
+  version '19.0'
+  source_url 'http://www.erlang.org/download/otp_src_19.0.tar.gz'
+  source_sha1 '3be958b529de4be19d77eb77f587a76210b43bfd'
+
+  def self.build
+    system 'export ERL_OTP=`pwd`'
+    system './configure --prefix=/usr/local'
+    system 'make'
+  end
+
+
+  def self.install
+    system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
+  end
+end