Fix: process.execute() now returns something.

process.execute() now reuturn exit code and output of the process, as it
should be.
isLocalhost() added.
Added support for local execution.

If the host in the execute() command is the localhost, the command is
executed locally and no connection is created.
A user for a remote connection is now required.
Added a convenience function.

Added a function that tests whether a file exists. The filetype can be
specified through an enumeration called fileTypes. Another function test
stub added for a function that tests whether a directory is empty.