User class

First pass at extending LBModel to implement LBUser to manage a User
account on the server.
User updated with proper access token handling.

An access token is now created upon successful User login and treated
as session credentials. This token is registered with the REST adapter
and set in the HTTP header for all subsequent REST calls.  Logout will
clear this token.
Cleanup

Remove a commented out test.
LBFile WIP

Work in progress for LBFile iOS support.
LBContainer

Implement the remaining portions of LBContainer and integration with
LBFile.
Unit testing for Container, User and File

First pass at units for exercising base functionality for LBContainer,
LBUser and LBFile.  Note: currently there isn’t a single node app that
supports all of the types (models, users, containers, etc).
LBFile cleanup and switch to streaming upload

Clean up a few issues including removing some copy/paste mistakes with
upload and download.  Remove the idea of fileData (that was loading the
file to be uploaded in memory first) and replace with a streaming
option.
Merge pull request #3 from sphess/master

User class