Bump version to 3.1.0

Set version to 3.0.0

Rename to cordova-plugin-zip and bump to v2.1.1

Set version for 2.1.0

Resolve unzip() URL arguments to file locations (fixes: MobileChromeA…

…pps#15)

Cleanup PR MobileChromeApps#14: Handle null returns from mapUriToFile.