Add theory on reproducible builds

[dbosk]

From @dbosk on May 8, 2015 15:57

Add David A Wheeler's work on countering Trusting Trust [Wheeler] to the theory section. Also incorporate this into the lab at a whole.

Copied from original issue: dbosk/malwarelab#1

[dbosk]

Also add news examples such that Juniper's ScreenOS contained unauthorized code which allowed adversary to decrypt VPN traffic etc.

[dbosk]

One example using reproducible builds is Signal.