Add a WorkspaceSettings.xcsettings in the RNTester project to turn off new Xcode build system. (#15)

* Added WorkspaceSettings.xcsettings file to RNTester.xcodeproj to ensure project builds from IDE using legacy build system instead of new build system which RN is not compatible with.:

* Unsaved changes

Author: tom-un

.gitignore

@@ -19,7 +19,10 @@ DerivedData
 *.hmap
 *.ipa
 *.xcuserstate
-project.xcworkspace
+# exclude project.xcworkspace except for xcshareddata/WorkspaceSettings.xcsettings
+project.xcworkspace/*
+**/project.xcworkspace/contents.xcworkspacedata
+**/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
 
 # Gradle
 /build/

RNTester/RNTester.xcodeproj/project.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+</dict>
+</plist>