Introducing basic share functionallity for iOS

This commit introduced basic share functionallity based on [1], this enables
users to share urls so far.

[1] https://github.com/vleango/GooglePlus-PhoneGap-iOS/blob/master/src/ios/GPlus.m
Adding googlePlus.bundle to iOS

Google+ share functionallity requires googlePlus.bundle to be provided.
Adding missing share export to javascript API

This commit exposes the newly introduced share functionallity to the plugin
API.
Adding basic share to Android

This commit allows the user to share some content, text and url are allowed
as of this commit.