Displays command line on failure

Issue: #49
Pull Request: #50

Runs --pre-script without the root privilege

Issue: #47
Pull Request: #48

Adds documentation

Issue: #45
Pull Request: #46

Adds --pre-script option

Issue: #43
Pull Request: #44

Adds --enable-vbguest option

Issue: #41
Pull Request: #42

Displays errors and warnings on the standard error output

Issue: #39
Pull Request: #40

Installs lsb_release package if it was not found

Issue: #37
Pull Request: #38

Cleans unnecessary configuration in the vagrantfile

Pull Request: #36

Creates custom files in the test directory

Pull Request: #35

Let vagrant use the best synced folder method

Pull Request: #34