Update sample scripts to gather 802.11ac data.

In more detail:

* ifstats now captures a system_profiler report on OS X, since the
  airport utility scan results don't distinguish between 802.11n and
  802.11ac networks.
* tcpdump now saves a raw packet capture, since the tcpdump command line
  doesn't process VHT headers in tested versions (OS X 10.10.3 and
* iperf now uses iperf3 in both directions.
* fabric env.always_use_pty is now False; this works around output
  streamed over ssh being incomplete for iperf3.
* An isostream test is now included and run by default.
* Added `timeout` shell script from
* Added IPv6 support, which was essentially a one-line change :)

Reporting changes to consume this data will follow in a separate CL.
We need to test networks day and night, and gathering the test data
immediately makes this easier to do.

Change-Id: Ida5c0a85005abe66243151f5531e5a014b86e4bb
6 files changed