Adds compatibility with ruby 2.0

Author: coding-chimp

.travis.yml

@@ -2,6 +2,7 @@ language: ruby
 cache: bundler
 
 rvm:
+  - 2.0.0
   - 2.1.0
   - 2.2.0
   - 2.3.0

lib/onesignal/client.rb

@@ -4,9 +4,11 @@ class Client
 
     attr_reader :auth_token, :app_id
 
-    def initialize(auth_token:, app_id: nil)
+    def initialize(auth_token: nil, app_id: nil)
       @auth_token = auth_token
       @app_id = app_id
+
+      ensure_auth_token_presence
     end
 
     def apps
@@ -27,8 +29,16 @@ def notifications
 
     private
 
+    def ensure_auth_token_presence
+      if auth_token.nil?
+        raise ArgumentError, 'missing keyword: auth_token'
+      end
+    end
+
     def ensure_app_id_presence
-      raise AppIdMissingError if app_id.nil?
+      if app_id.nil?
+        raise AppIdMissingError
+      end
     end
   end
 end

onesignal.gemspec

@@ -19,6 +19,8 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
+  spec.required_ruby_version = '>= 2.0.0'
+
   spec.add_development_dependency 'bundler', '~> 1.11'
   spec.add_development_dependency 'minitest', '~> 5.0'
   spec.add_development_dependency 'rake', '~> 10.0'