[Lockfile] Fix specs for grammar change.

spec/integration_spec.rb

@@ -305,7 +305,7 @@ else
           # lockfile_contents['PODS'][0] = 'ASIHTTPRequest (1.8.1)'
         end
         result = installer.lockfile.to_hash
-        result.delete("SPECS CHECKSUM")
+        result.delete("SPEC CHECKSUMS")
         result.should == lockfile_contents
 
         root = config.project_pods_root

spec/unit/lockfile_spec.rb

@@ -15,7 +15,7 @@ PODS:
 DEPENDENCIES:
 - BananaLib (~> 1.0)
 
-SPECS CHECKSUM:
+SPEC CHECKSUMS:
   BananaLib: !binary |-
     MjI2Y2RkMTJkMzBhMWU4ZWM4OGM1ZmRkZWU2MDcwZDg0YTI1MGZjMQ==