Improve setup robustness of Windows tests

* In PowerShell scripts:
  * Use $ErrorActionPreference = 'Stop' so we stop on any error
  * Use Exec helper that throws an error on any errorlevel
  * Try not to use -ErrorAction SilentlyContinue as often

* In Python scripts:
  * Use powershell -Command instead of -File which does not propagate
    the errorlevel properly.
  * For stop(), use subprocess.check_call() which is synchronous and
    which can check the exit code, unlike subprocess.Popen() which
    is asynchronous.
Upgrade from Play 2.2.0-RC2 to 2.2.0
Updated to Play 2.2.0 along with 2.2.0 conventions
Updated to Play 2.2.0 along with 2.2.0 conventions
now PLAIN should run on Windows, too
Check if port is available before test start and after test stop

I have a theory that a Windows run was testing the wrong server, so
this change should report problems like this by checking to see if
the port is available before starting the test and after stopping
the test.
fixed db update to be compliant with the requirements
abort transaction if exception happens

otherwise the transaction remains in a autocommit=true
state and subsequent threads reusing it can't work
Update installer.py

Remove query string from downloaded filename
Merge pull request #550 from MalcolmEvershed/windows-setup-robustness

Improve setup robustness of Windows tests
Merge pull request #552 from MalcolmEvershed/check-port-available

Check if port is available before test start and after test stop
Preview Run 3 (ramdisk-backed) raw wrk files
Merge https://github.com/TechEmpower/FrameworkBenchmarks into development
Update README.md

Updated ports (see issue #549)
Merge pull request #551 from huntc/play-2-2-0

Play 2 2 0 updates
Merge pull request #553 from weltermann17/master

Plain: fixed db update to be compliant with the requirements
Merge pull request #554 from oberhamsi/fix-ringo-mysqldeadlock

ringojs: less error requests in "updates" test
Merge pull request #555 from tcrossland/patch-1

Update installer.py
fix "versus" in benchmark_config
Merge pull request #556 from oberhamsi/patch-2

fix "versus" in benchmark_config