Summary:
Add more flexibility to the iOS UIExplorer test scripts:
- support environments without `xcpretty` installed
- support custom xcode destination argument
Initial PR is based on the last git commit which passed on Travis today (2a92b52) in order to test Travis build.
I'll rebase to latest, in order to fix merge conflicts, before merging.
**Test plan (required)**
Make sure tests pass on Travis.
Closes https://github.com/facebook/react-native/pull/7982
Differential Revision: D3404574
Pulled By: avaly
fbshipit-source-id: 48aabd81fba67d482af46728a9c3975842f03060
Summary:The Obj-C tests were stalling when we updated TravisCI to use the OS X image with Xcode 7.3 and iOS 9.3.
On my own MBP with Xcode 7.3 the tests stall as well. Running `./scripts/objc-test.sh` prints out a warning near the end, which says `ld` couldn't find a Frameworks folder under the iPhoneSimulator9.3 SDK directory. Indeed, this directory doesn't exist on my computer. When creating a brand new project with unit tests and UI tests, both test targets don't specify "Framework Search Paths" so I don't think we need to specify it anymore.
Closes https://github.com/facebook/react-native/pull/7168
Differential Revision: D3216524
fb-gh-sync-id: 3097bda98d78289ecdba86801bcd461f3311ac47
fbshipit-source-id: 3097bda98d78289ecdba86801bcd461f3311ac47