Android MP3 Player / MP3 Downloader

Hello, we need a developer for an Android application. The application will be a part of our web service. Here is the description of the features: - Login / Registration for a user (simple email and password / no double opt-in) - Play and download mp3 files / playlists (the files links will be sent by the server with an JSON object) - Settings menu (file destination, change password, logout) - Google Wallet SDK (payment for user) The apps tabs are divided in the following categories: - Categories (music genres, will be sent by the server - a click will open a new intent with music files in it / user can play and download them) - Playlist (user can add/remove a playlist our a song in it) - Search (sends a search request to our server and get a JSON-response) - MP3-Player (plays the files from a playlist) As I already wrote, the app must communicate with our webserver by an JSON-Api. It will get all the file information by the API. User must be logged in (on a successful login, server reponses an session id).