VBOX: Attempt to gracefully fallback to using vboxmanage when the COM interface cannot be successfully created.

The scratch directory is created under the project folder.

VBOX: If <disable_automatic_checkpoints/> is specified, automatically report completed checkpoints to the client as soon as the API requests them.

VBOX: If polling for the current VM state fails for any reason, like vboxsvc crashing, do a temp exit for 24 hours.

Before COM, polling for the current state wasn't as critical.  If the poll operation failed, we would try again in one second anyway.

After COM, it is used as a test to see if the communication channel between the wrapper and VirtualBox is still operational.  If not, temp exit and hope things work the next attempt.

Projects may want to handle check-pointing within their own application and skip the disk intensive requirements of a VM snapshot.

VBOX: Make creating/writing the graphics status file part of the job file configuration.  No need to write it if there is not going to be a running graphics application.

VBOX: Introducing a basic graphics application for vboxwrapper based on HTML rendering. Basic plumbing is done.

TODO:
* Add vbox job elements to point to various URLs for various states. (running/suspended/not running)
* Add window timer to poll for shared memory changes
* Exit if running in screen saver mode and keyboard/mouse activity is detected.

VBOX: Make the service install scenario work again.

VBOX: last_checkpoint_cpu_time != last_checkpoint_elapsed_time.  When to checkpoint is based on elapsed time, what we reported to boinc is the cpu time.  Keep track of both values.

VBOX: Introduce the notion of Virtualbox COM namespaces. We currently support VirtualBox 4.2 and VirtualBox 4.3.

When the file is detected, the wrapper will call boinc_temporary_exit() and restart the VM at a later date.

VBOX: Move common code to VBOX_BASE class, VBOX_VM derives from it by extending virtual functions calling Vboxmanage or Native API functions.  Use ATL on Windows to wrap COM Objects and data types.

When the file is detected, the wrapper will call boinc_temporary_exit() and restart the VM at a later date.