Use new authorization URL and exchange authroization code URL

As described on https://developer.linkedin.com/docs/oauth2, the old URLs are
considered "legacy".

Author: SteveLTN

lib/omniauth/strategies/linkedin.rb

@@ -10,8 +10,8 @@ class LinkedIn < OmniAuth::Strategies::OAuth2
       # initializing your consumer from the OAuth gem.
       option :client_options, {
         :site => 'https://api.linkedin.com',
-        :authorize_url => 'https://www.linkedin.com/uas/oauth2/authorization?response_type=code',
-        :token_url => 'https://www.linkedin.com/uas/oauth2/accessToken'
+        :authorize_url => 'https://www.linkedin.com/oauth/v2/authorization?response_type=code',
+        :token_url => 'https://www.linkedin.com/oauth/v2/accessToken'
       }
 
       option :scope, 'r_basicprofile r_emailaddress'

spec/omniauth/strategies/linkedin_spec.rb

@@ -14,11 +14,11 @@
     end
 
     it 'has correct authorize url' do
-      expect(subject.client.options[:authorize_url]).to eq('https://www.linkedin.com/uas/oauth2/authorization?response_type=code')
+      expect(subject.client.options[:authorize_url]).to eq('https://www.linkedin.com/oauth/v2/authorization?response_type=code')
     end
 
     it 'has correct token url' do
-      expect(subject.client.options[:token_url]).to eq('https://www.linkedin.com/uas/oauth2/accessToken')
+      expect(subject.client.options[:token_url]).to eq('https://www.linkedin.com/oauth/v2/accessToken')
     end
   end