Fix capitalization for header auth keys

Fix capitalization for header auth keys

diff --git a/lib/discourse_api/client.rb b/lib/discourse_api/client.rb
index e4d6fc2..233a115 100644
--- a/lib/discourse_api/client.rb
+++ b/lib/discourse_api/client.rb
@@ -59,7 +59,7 @@ module DiscourseApi
 
     def api_username=(api_username)
       @api_username = api_username
-      @connection.headers['Api-username'] = api_username unless @connection.nil?
+      @connection.headers['Api-Username'] = api_username unless @connection.nil?
     end
 
     def connection_options
@@ -122,8 +122,8 @@ module DiscourseApi
         conn.adapter Faraday.default_adapter
         #pass api_key and api_username on every request
         unless api_username.nil?
-          conn.headers['Api-key'] = api_key
-          conn.headers['Api-username'] = api_username
+          conn.headers['Api-Key'] = api_key
+          conn.headers['Api-Username'] = api_username
         end
       end
     end

GitHub sha: 64476cc1