[#1871] Parse test arguments from buildbot.

Problem description
===================

```paver test``` is our main test command and we use it on buildslaves.

```paver test_remote``` can send arguments to remote tests but all arguments are enclosed into a single argument, due to the way buildbot works. 


Changes description
===================

If paver test receive a single argument it will try to split it by spaces.

In this way

```
paver test normal --attr='!slow' -x

is the same as

paver test "normal --attr='!slow`  -x"

```

How to try and test the changes
===============================

reviewers @alibotean

Run paver test_remote using multipe argumetns.

example

```
paver test_remote win-xp-x86 -x -v --with-timer
```

Thanks!