Update unit tests and clean up generator code

lib/cocoapods/generator/xcconfig/aggregate_xcconfig.rb

@@ -49,7 +49,7 @@ module Pod
           'OTHER_LDFLAGS' => XCConfigHelper.default_ld_flags(target),
           'PODS_ROOT' => target.relative_pods_root,
           'GCC_PREPROCESSOR_DEFINITIONS' => '$(inherited) COCOAPODS=1',
-          'OTHER_CFLAGS' => '$(inherited)' + XCConfigHelper.quote(header_search_path_flags)
+          'OTHER_CFLAGS' => '$(inherited) ' + XCConfigHelper.quote(header_search_path_flags)
         })
 
         target.pod_targets.each do |pod_target|

spec/unit/generator/xcconfig/aggregate_xcconfig_spec.rb

@@ -55,13 +55,8 @@ module Pod
           @xcconfig.to_hash['PODS_ROOT'].should == '${SRCROOT}/Pods'
         end
 
-#         it 'adds the sandbox public headers search paths to the xcconfig, with quotes' do
-#           expected = "\"#{config.sandbox.public_headers.search_paths.join('" "')}\""
-#           @xcconfig.to_hash['HEADER_SEARCH_PATHS'].should == expected
-#         end
-        
         it 'adds the sandbox public headers search paths to the xcconfig, with quotes, as system headers' do
-          expected = "\"-isystem#{config.sandbox.public_headers.search_paths.join('" -isystem"')}\""
+          expected = "$(inherited) \"-isystem#{config.sandbox.public_headers.search_paths.join('" -isystem"')}\""
           @xcconfig.to_hash['OTHER_CFLAGS'].should == expected
         end