Add headers option on RemoteFile/Http

- Add an option :headers key for the caller to provide custom headers

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    cocoapods-downloader (1.2.2)
+    cocoapods-downloader (1.2.3)
 
 GEM
   remote: https://rubygems.org/

lib/cocoapods-downloader/gem_version.rb

@@ -3,6 +3,6 @@ module Downloader
     # @return [String] Downloader’s version, following
     #         [semver](http://semver.org).
     #
-    VERSION = '1.2.2'.freeze
+    VERSION = '1.2.3'.freeze
   end
 end

lib/cocoapods-downloader/http.rb

@@ -8,7 +8,14 @@ class Http < RemoteFile
       executable :curl
 
       def download_file(full_filename)
-        curl! '-f', '-L', '-o', full_filename, url, '--create-dirs', '--netrc-optional', '--retry', '2'
+        parameters = ['-f', '-L', '-o', full_filename, url, '--create-dirs', '--netrc-optional', '--retry', '2']
+
+        headers.each do |h|
+          parameters << '-H'
+          parameters << h
+        end unless headers.nil?
+
+        curl! parameters
       end
     end
   end

lib/cocoapods-downloader/remote_file.rb

@@ -6,7 +6,7 @@ module Pod
   module Downloader
     class RemoteFile < Base
       def self.options
-        [:type, :flatten, :sha1, :sha256]
+        [:type, :flatten, :sha1, :sha256, :headers]
       end
 
       class UnsupportedFileTypeError < StandardError; end
@@ -35,6 +35,10 @@ def type
         end
       end
 
+      def headers
+        options[:headers]
+      end
+
       # @note   The archive is flattened if it contains only one folder and its
       #         extension is either `tgz`, `tar`, `tbz` or the options specify
       #         it.