CIMI: Added database support for MachineImage

* Properties and description are now stored in database
* ImageLocation is now reported correctly
* Creation time is now reported correctly
Core: Remove 'set' in deltacloudd when thin is not installed
Core: Print warning when starting as a daemon without thin
Core: Change directory to $top_srcdir when using Webrick
Core: Overide default Rack::Server server to use :webrick
Core: Initial tests for deltacloudd launcher

- Starts a Deltacloud APi instance on port 3011
- Checks if DC is running (respond to HTTP requests)
- Checks if DC could be started with multiple frontends