Try Travis builtin support for Cocoapods & xctool

.travis.yml

@@ -1,12 +1,18 @@
 language: objective-c
-before_install:
-  - brew install gflags
 env:
   global:
     - CONFIG=opt
     - TEST=objc
     - JOBS=1
-script:
-  - ./tools/run_tests/run_tests.py -l $TEST -t -j $JOBS -c $CONFIG -s 4.0
+before_install:
+  - brew install gflags
+  - make grpc_objective_c_plugin
+  - make interop_server
+podfile: src/objective-c/tests/Podfile
+before_script:
+  - bins/$CONFIG/interop_server --port=5050 &
+  - bins/$CONFIG/interop_server --port=5051 --use_tls &
+xcode_workspace: src/objective-c/tests/Tests.xcworkspace
+xcode_scheme: AllTests
 notifications:
   email: false