Get Azure maximum part size dynamically
Get Azure maximum part size dynamically

This size will increase from 4 to 100 MB in jclouds 2.1.0.
References #191.  Follow on to 2ddce6af869dedc744cbdf5aa7fd174333bd981e.

timuralp/s3proxy,andrewgaul/s3proxy,timuralp/s3proxy,andrewgaul/s3proxy