(1) Added yum timeout of 120 seconds. (2) postBuffer patch. (3) Typo fix...

So after running a ton more tests and experiencing lots of build failures, most of the errors came to one of two things: 

1. a timeout from some package install, usually from the Euca repos. Fixed by adding "timeout=120" in /etc/yum.d in eucadev.sh (default setting is 30).  After adding this fix, had no more problems with yum, ever.

2. a weird hangup from Github with the error "error: RPC failed; result=56, HTTP code = 200". Google says that setting git's http.postBuffer value on the client generally fixes this, so I added that fix.  No problems since.

I have successfully built 5 more times from packages with no errors, although I do still get timeout failures building from source, which I will investigate further.