Add build script for continuous integration

The script is based on the build script for copper
https://git.opnfv.org/cgit/releng/tree/jjb/copper/docu-build.sh
The script should be run from the root of kvmfornfv source tree

Change-Id: Ic12890990741441e88e35a87ef2570b1c601ca61
Signed-off-by: David Su <david.w.su@intel.com>