[BEHAVIORAL-CHANGE] Template contents being verified in master

[Marcus <sh...@gmail.com>]

Just a heads-up that I've committed a small bit of code to master that
verifies template contents when downloading (per CLOUDSTACK-6088). For
example, it verifies that the first few bytes of a template registered as a
vhd format look like a vhd file. This is designed to catch mis-matches, and
in particular uploads of .vmdk where the user is really uploading the ASCII
text descriptor and not the FLAT vmdk data file.

The commit is fairly small, but I'm a bit nervous that I may not have
accounted for all incarnations of what various formats might look like, so
I thought I'd send out a heads-up. If your template registrations start
complaining about mismatched types we can fix or roll this back.

commit 15ac47e47b4c9a2323888d73f6988cb967647e28
Author: Marcus Sorensen <ma...@betterservers.com>
Date:   Wed May 28 15:36:13 2014 -0600

    CLOUDSTACK-6088: Check first bytes of template when downloading to
verify format/type