Updated travis to run using xcode 9.2 (google#676)

* Updated travis to 9.3

* update sdk to 11.2

* fix error and update sim runtime for Xcode 9.2 runs

* iOS 11 is changed to 11.0.1 for Xcode 9.2

Fix for failure caught on travis as it's missing 11.0 instead it has 11.0.1

* Add installation of cocoapods to travis script

Seems to be missing it from Xcode 9.2 machines:
https://travis-ci.org/google/EarlGrey/jobs/334905483

```
+pod install --project-directory=Demo/EarlGreyExample
Scripts/travis.sh: line 104: pod: command not found
```

* runtime 10.3 => 10.3.1 for Xcode 9.2

Travis doesn't have 10.3 on machines that have Xcode 9.2 installed.

Author: khandpur

.travis.yml

@@ -40,27 +40,27 @@ matrix:
         - DESTINATION="OS=9.1,name=iPhone 6s" SDK=iphonesimulator9.3 TYPE="UNIT"
     - env:
         - DESTINATION="OS=9.3,name=iPhone 6s Plus" SDK=iphonesimulator9.3 TYPE="FUNCTIONAL"
-    - osx_image: xcode8.2
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPhone 6s" SDK=iphonesimulator10.2 TYPE="CARTHAGE"
-    - osx_image: xcode8.2
+        - DESTINATION="OS=10.1,name=iPhone 6s" SDK=iphonesimulator11.2 TYPE="CARTHAGE"
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPhone 7 Plus" SDK=iphonesimulator10.2 TYPE="EXAMPLE_PODS"
-    - osx_image: xcode8.2
+        - DESTINATION="OS=10.2,name=iPhone 7 Plus" SDK=iphonesimulator11.2 TYPE="EXAMPLE_PODS"
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPhone 7 Plus" SDK=iphonesimulator10.2 TYPE="EXAMPLE_PODS_SWIFT"
-    - osx_image: xcode8.2
+        - DESTINATION="OS=10.3.1,name=iPhone 7 Plus" SDK=iphonesimulator11.2 TYPE="EXAMPLE_PODS_SWIFT"
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPhone 7" SDK=iphonesimulator10.2 TYPE="FUNCTIONAL"
-    - osx_image: xcode8.2
+        - DESTINATION="OS=11.0.1,name=iPhone 7" SDK=iphonesimulator11.2 TYPE="FUNCTIONAL"
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPad Air" SDK=iphonesimulator10.2 TYPE="FUNCTIONAL_SWIFT"
-    - osx_image: xcode8.2
+        - DESTINATION="OS=11.2,name=iPad Air" SDK=iphonesimulator11.2 TYPE="FUNCTIONAL_SWIFT"
+    - osx_image: xcode9.2
       env:
-        - DESTINATION="OS=10.2,name=iPhone 7 Plus" SDK=iphonesimulator10.2 TYPE="UNIT"
+        - DESTINATION="OS=11.2,name=iPhone 7 Plus" SDK=iphonesimulator11.2 TYPE="UNIT"
     - env:
       - TYPE="RUBY"
-    - osx_image: xcode8.3
+    - osx_image: xcode9.2
       env:
       - TYPE="PACKAGE"
 before_install:

Scripts/travis.sh

@@ -19,6 +19,8 @@ set -euxo pipefail
 xcodebuild -version
 xcodebuild -showsdks
 
+gem install cocoapods
+
 CONFIG="Debug"
 ACTION="test"