Improve error message/handling

[bheuvel]

Improve error reporting to the user by error handling, thereby preventing the raw stacktraces

Build on #169
Closes #163

Considering the limited number of people doing PR validation, please aprove the latest PR in this change, which will effectively aprove all PRs.

[coveralls]

Changes Unknown when pulling 258d1a3 on fix/163_improve_errormessage into ** on master**.

[coveralls]

Changes Unknown when pulling 390c6f8 on fix/163_improve_errormessage into ** on master**.

[coveralls]

Changes Unknown when pulling 9d8e56c on fix/163_improve_errormessage into ** on master**.

[bheuvel]

Running RSpec tests in folder : vmlifecycle
Using Vagrant file            : Vagrantfile.advanced_networking

VM Life Cycle
  starts Linux and Windows VM
  destroys Linux and Windows VM

Finished in 2 minutes 44.8 seconds (files took 0.13638 seconds to load)
2 examples, 0 failures

Running RSpec tests in folder : networking
Using Vagrant file            : Vagrantfile.advanced_networking

Networking features
  creates firewall and portwarding rules for both Virtual Router and VPC

Finished in 2 minutes 54 seconds (files took 0.08635 seconds to load)
1 example, 0 failures

Running RSpec tests in folder : rsync
Using Vagrant file            : Vagrantfile.advanced_networking

VM RSync
  does rsync to the VM

Finished in 48.3 seconds (files took 0.09241 seconds to load)
1 example, 0 failures