Use the Scala wrapper for System.getProperty that returns Option.
Use stdlib's Future.zip for parallel Future execution.

Stdlib Future's already have a .zip method that executes them both in
parallel.
Cons: A useless intermediate tuple.
Merge pull request #577 from LeifW/use_future_zip

Use future zip
remove `implicit` modifier from `fromScalaOrdering`

Closes #358.
wip update Scalacheck 1.11.0

specs2 1.12.x depends on scalacheck 1.9

https://github.com/scalaz/scalaz/blob/v7.1.0-M3/project/build.scala#L293-L295
https://github.com/etorreborre/specs2/blob/SPECS2-1.12.3/build.sbt#L30
https://github.com/etorreborre/specs2/blob/SPECS2-1.12.4/build.sbt#L30

```
[error] bad symbolic reference. A signature in ScalaCheckParameters.class refers to term Pretty
[error] in package org.scalacheck which is not available.
[error] It may be completely missing from the current classpath, or the version on
[error] the classpath might be incompatible with the version used when compiling ScalaCheckParameters.class.
[error] bad symbolic reference. A signature in ScalaCheckParameters.class refers to type Params
[error] in value org.scalacheck.Pretty which is not available.
[error] It may be completely missing from the current classpath, or the version on
[error] the classpath might be incompatible with the version used when compiling ScalaCheckParameters.class.
```