Add exec methods with command array on WindowsExec

### Context
On Windows platform, the decoding of command strings specified to ```Runtime.exec(String)```, ```Runtime.exec(String,String[])``` and ```Runtime.exec(String,String[],File)``` methods, has been improved to follow the specification more closely. This may cause problems for applications that are using one or more of these methods with commands that contain spaces in the program name, or are invoking these methods with commands that are not quoted correctly.

see: http://www.oracle.com/technetwork/java/javase/6u45-relnotes-1932876.html

As a consequence commands with redirection in a single string don't work anymore.

### Description
Methods on ```WindowsExec``` with commands array has been added.
Exemple
```executor.exec(new String[]{"cmd.exe", "/C", "dir > result.txt"}, new File("target"));```