Updated with info about possibility of tracking upload progress

Before to know this, you'll have to inspect sources or try different auto-completes in IDE.
Merge pull request #58 from chester1000/master

Updated with info about possibility of tracking upload progress
Update README.md
add some logging for when a context dies

Change-Id: Idcfae97150bb6ef45af8b922d4bafa15dd8a1d6c