iOS Network test, callbacks, project install, cropping.

iOS Only

• Additional OpenTok callback hooks have been added in. See README.
• Added in the ability to start an OpenTok network test from JS.
• Cropped portrait video input to a square.
• Moved to be a project dependency vs. pod install.
• Numerous stabilization & bug fixes.

First Integratabtle Version

Includes #1, #2, #3, #4, #5, #6

Usable with use_frameworks in Podfile of app. Tokbox must be installed as a separate pod dependency at the same level as react-native-opentok in order to work.

Initial Release

Release of initial fork from https://github.com/callstack-io/react-native-opentok of commit adfb620