Command Injection in pidusage

Affected versions of `pidusage` pass unsanitized input to `child_process.exec()`, resulting in arbitrary code execution in the `ps` method.

This package is vulnerable to this PoC on Darwin, SunOS, FreeBSD, and AIX.

Windows and Linux are not vulnerable.

## Proof of Concept
```
var pid = require('pidusage');
pid.stat('1 && /usr/local/bin/python');
```

## Recommendation

Update to version 1.1.5 or later.