action: Added 'is_driver_version' middleware
guest_cap: Fixed typo in the cabability name
driver: Refactoring. Modified 'execute' method. Added 'execute_prlctl' & 'execute_prlsrvctl' wrappers
errors: Renamed 'PrlCtlError' -> 'ExecutionError'
errors: Fixed text for 'mac_os_x_required' error
driver: Added 'read_guest_tools_iso_path' method
action: 'CheckGuestTools' replaced with 'HandleGuestTools'

'HandleGuestTools' supports checking and installing/updating guest tools as well
guest_cap: Added "install_parallels_tools" capability for linux guests [GH-70]
action/set_power_consumption: Removed PD version checking.

Use 'IsDriverVersion' middleware instead.
errors: Text for 'VMImportFailure' customized.

Default message from vagrant contains a virtualbox-specific phrase
Version bumped to v1.1.0