[CB-2638] Fix iOS project warnings on Retina imgs

-fixed iphone and ipad 2x images to remove warnings
-ran images thru imageoptim
Fixed static analyzer issues.
[CB-1933] Changed button labels to an array.

This allows commas to be included in button label text.
Changed UIWebViewBounce to DisallowOverscroll.

Both are supported, but the default preference name is changed to align
with Android.
[CB-1688] Added a camera direction option.
CB-2491: Deprecate current Connection cell setting

- adds deprecation notice and recognize CELL setting
[CB-2195] Remove deprecated - iOS - BackupWebStorage Cordova.plist property change from boolean to string
[CB-2194] Remove deprecated - iOS - CDVCommandDelegate registerPlugin method
Use noCopy versions of NSString init in Base64 code.
Add an associatedObject field to CDVPluginResult.

Could have used objc_setAssociatedObject, but this seems simpler since
we own the class.
[CB-2652] Make FileReader.readAs*() functions run on a background thread

Also refactored to remove copy/paste.
[CB-2633] Add FileReader.readAsBinaryString()