[Gemspec] Update Xcodeproj dependency to `~> 0.20.0`

Gemfile.lock

@@ -25,10 +25,10 @@ GIT
 
 GIT
   remote: https://github.com/CocoaPods/Xcodeproj.git
-  revision: ff7c70da5f5082eef47bb248012b69c76f6c6e54
+  revision: bd13b322da2f4561304f60543c92608583b016dd
   branch: master
   specs:
-    xcodeproj (0.19.4)
+    xcodeproj (0.20.0)
       activesupport (~> 3.0)
       colored (~> 1.2)
 
@@ -49,7 +49,7 @@ GIT
 
 GIT
   remote: https://github.com/CocoaPods/cocoapods-trunk.git
-  revision: aee318675961e0666af80a67596497de62b68c2e
+  revision: 418085ebd393426cc6ab16e646ae0663921dbe81
   branch: master
   specs:
     cocoapods-trunk (0.3.1)
@@ -81,7 +81,7 @@ PATH
       molinillo (~> 0.1.0)
       nap (~> 0.8)
       open4 (~> 1.3)
-      xcodeproj (~> 0.19.4)
+      xcodeproj (~> 0.20.0)
 
 GEM
   remote: http://rubygems.org/
@@ -106,7 +106,7 @@ GEM
     escape (0.0.4)
     ffi (1.9.6)
     fuzzy_match (2.0.4)
-    i18n (0.6.4)
+    i18n (0.6.11)
     json_pure (1.8.1)
     kicker (3.0.0)
       listen (~> 1.3.0)

cocoapods.gemspec

@@ -29,7 +29,7 @@ Gem::Specification.new do |s|
   # Link with the version of CocoaPods-Core
   s.add_runtime_dependency 'cocoapods-core',       "= #{Pod::VERSION}"
   s.add_runtime_dependency 'claide',               '~> 0.7.0'
-  s.add_runtime_dependency 'xcodeproj',            '~> 0.19.4'
+  s.add_runtime_dependency 'xcodeproj',            '~> 0.20.0'
   s.add_runtime_dependency 'cocoapods-downloader', '~> 0.7.2'
   s.add_runtime_dependency 'cocoapods-plugins',    '~> 0.3.1'
   s.add_runtime_dependency 'cocoapods-try',        '~> 0.4.1'

lib/cocoapods/generator/acknowledgements/plist.rb

@@ -6,7 +6,6 @@ module Pod
       end
 
       def save_as(path)
-        require 'xcodeproj/ext'
         Xcodeproj.write_plist(plist, path)
       end