Update travis to use CocoaPods 1.4.0 (firebase#692)

Author: paulb777

Gemfile.lock

@@ -1,12 +1,12 @@
 GIT
   remote: https://github.com/CocoaPods/CocoaPods.git
-  revision: 88276c47b6b57f423f9ded45e0df29c53cadc71d
+  revision: df6872de04fd1808fde71c824530e3a784e6a2d2
   specs:
-    cocoapods (1.4.0.rc.1)
+    cocoapods (1.4.0)
       activesupport (>= 4.0.2, < 5)
       claide (>= 1.0.2, < 2.0)
-      cocoapods-core (= 1.4.0.rc.1)
-      cocoapods-deintegrate (>= 1.0.1, < 2.0)
+      cocoapods-core (= 1.4.0)
+      cocoapods-deintegrate (>= 1.0.2, < 2.0)
       cocoapods-downloader (>= 1.1.3, < 2.0)
       cocoapods-plugins (>= 1.0.0, < 2.0)
       cocoapods-search (>= 1.0.0, < 2.0)
@@ -24,19 +24,20 @@ GIT
 
 GIT
   remote: https://github.com/CocoaPods/Core.git
-  revision: 33299ada83b98e1c7ec117f4d4d67055b2247a19
+  revision: b4fb2f193897c789c094d126ebca91034edc261d
   specs:
-    cocoapods-core (1.4.0.rc.1)
+    cocoapods-core (1.4.0)
       activesupport (>= 4.0.2, < 6)
       fuzzy_match (~> 2.0.4)
       nap (~> 1.0)
 
 GIT
   remote: https://github.com/CocoaPods/Xcodeproj.git
-  revision: 976144e24bd68a7f34fbfeeeb6b408cfda247fdd
+  revision: 531d8aa8ab4805c84f5e0fe94181ae3995430d05
   specs:
     xcodeproj (1.5.4)
       CFPropertyList (~> 2.3.3)
+      atomos (~> 0.1.0)
       claide (>= 1.0.2, < 2.0)
       colored2 (~> 3.1)
       nanaimo (~> 0.2.3)
@@ -50,8 +51,9 @@ GEM
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
+    atomos (0.1.0)
     claide (1.0.2)
-    cocoapods-deintegrate (1.0.1)
+    cocoapods-deintegrate (1.0.2)
     cocoapods-downloader (1.1.3)
     cocoapods-plugins (1.0.0)
       nap
@@ -67,7 +69,7 @@ GEM
     fourflusher (2.0.1)
     fuzzy_match (2.0.4)
     gh_inspector (1.0.3)
-    i18n (0.9.1)
+    i18n (0.9.3)
       concurrent-ruby (~> 1.0)
     minitest (5.11.1)
     molinillo (0.6.4)