React Native build phases / start script + NewsFeedView RefreshControl

[aaronschachter]

• Adds a start script to package.json for easier local React Native development
• Adds a build phase for easier React Native bundling (closes Build step for compiling React main.jsbundle #752 - refs News feed summary item image #764 which adds images twice). This basically just calls react-native bundle, using the react-native/packager/react-native-xcode.sh as a reference
• Untracks the main.jsbundle file, since we bundle it within said new build step upon each build - closes Untrack and remove main.jsbundle from repo #763
• Removes unused main.jsbundle in root directory - closes 2 main.jsbundles exist #762
• Adds a RefreshControl which allows user to get updated News Feed by manually pulling to refresh. Safe to say that this closes NewsFeed - check for updates #737 for now

TODO:

• Update wiki

[aaronschachter]

Not sure we even need a timeout at all here.