Add options to set headers when initializing client

README.md

@@ -36,6 +36,11 @@ Optional arguments: `gzip: true`
 ```ruby
 client = Exponent::Push::Client.new
 # client = Exponent::Push::Client.new(gzip: true)  # for compressed, faster requests
+# client = Exponent::Push::Client.new(headers: {
+#  'Content-Type' => 'application/json',
+#  'Accept' => 'application/json',
+#  'Authorization' => 'Bearer ACCESS_TOKEN',
+# })  # to set or update headers
 
 messages = [{
   to: "ExponentPushToken[xxxxxxxxxxxxxxxxxxxxxx]",

lib/exponent-server-sdk.rb

@@ -42,6 +42,7 @@ def initialize(**args)
         # future versions will deprecate this
         @response_handler = args[:response_handler] || ResponseHandler.new
         @gzip             = args[:gzip] == true
+        @headers          = args[:headers] ? headers.merge!(args[:headers]) : headers
       end
 
       # returns a string response with parsed success json or error
@@ -77,7 +78,7 @@ def push_notifications(messages)
         @http_client.post(
           push_url,
           body: messages.to_json,
-          headers: headers,
+          headers: @headers,
           accept_encoding: @gzip
         )
       end
@@ -90,7 +91,7 @@ def get_receipts(receipt_ids)
         @http_client.post(
           receipts_url,
           body: { ids: receipt_ids }.to_json,
-          headers: headers,
+          headers: @headers,
           accept_encoding: @gzip
         )
       end