added interfaces for the document providers
added a module for a filesystem provider
simplified document browser interfaces
added compatibility classes
added an adapter for an SAF documents provider
renamed DocumentBrowser to DocumentsProvider
added a file system provider implementation based on https://github.com/ianhanniballake/LocalStorage
added a SAF documents adapter for file system
integrated file system documents adapter into example app
added id for provider and support for cursor adapter (_id)
added a module for document picker ui that uses file system provider
added a registry for document providers
added helper classes to deal with root and document cursors
using provider and document picker in example app
updated versions
Merge pull request #1 from mobilejazz/provider/filesystem

Setting up the library to support UIs and providers