Fix NPE crashes.

• Use asynctasks for running in background and UI threads for getting images/videos from gallery.
• Fix crash where I would not return from function if user cancelled camera/gallery intent.

Get photos/videos from device gallery.

• Allow user to get photo/video from gallery.
• Update example app to demonstrate the ability to get photos and videos from gallery.
• Update README to reflect the ability to get photos/videos from gallery and prepare for a more formal release.

Capture images from camera.

First release for Shutter-Android library.

• Create Shutter library to be able to capture photos from camera.
• Optionally, declare filename, where you would like to save photos to.
• Create example app.
• README chats about how to use library.