blueprint migrate-to-diskimage-builder

Incorporated code review comments
- removed IDE specific values from .gitignore
- moved SSH Key creation into redstack/functions_qemu script
- removed dead files
- added GUEST_USERNAME if needed to override (otherwise inherits host username)
- cleaned up MySQL startup so that it does not start initially

Added "elements" directory which contains the parts to build a reddwarf-guest and reddwarf-mysql image
Modified "redstack" so that it installs diskimage-builder and copies elements to diskimage-builder directory (temp workaround)
Modified "redstack.rc" to point to diskimage-builder repository
Modified "functions_qemu" to replace ubuntu vm builder with diskimage-builder

Change-Id: Ifd6a28d94b3cc8d4d8dc6792d5db48b6ec57004d
Merge "blueprint migrate-to-diskimage-builder"