test refurb: removed xcpretty on travis + using yarn + e2e tests

Summary:
- switched to yarn on travis (experimental)
- removed xcpretty, we need more verbose logs
- returned jest test for e2e
Closes https://github.com/facebook/react-native/pull/10442

Differential Revision: D4043991

Pulled By: davidaurelio

fbshipit-source-id: 50062f6a77a17643bf9a7ba7add8cee5b3bb26d2

scripts/objc-test.sh

@@ -28,26 +28,12 @@ function cleanup {
 }
 trap cleanup EXIT
 
-# Support for environments without xcpretty installed
-set +e
-OUTPUT_TOOL=$(which xcpretty)
-set -e
-
 # TODO: We use xcodebuild because xctool would stall when collecting info about
 # the tests before running them. Switch back when this issue with xctool has
 # been resolved.
-if [ -z "$OUTPUT_TOOL" ]; then
-  xcodebuild \
-    -project $XCODE_PROJECT \
-    -scheme $XCODE_SCHEME \
-    -sdk $XCODE_SDK \
-    -destination "$XCODE_DESTINATION" \
-    test
-else
-  xcodebuild \
-    -project $XCODE_PROJECT \
-    -scheme $XCODE_SCHEME \
-    -sdk $XCODE_SDK \
-    -destination "$XCODE_DESTINATION" \
-    test | $OUTPUT_TOOL && exit ${PIPESTATUS[0]}
-fi
+xcodebuild \
+  -project $XCODE_PROJECT \
+  -scheme $XCODE_SCHEME \
+  -sdk $XCODE_SDK \
+  -destination "$XCODE_DESTINATION" \
+  build test