Merge pull request #1 from xueshanf/master

bin/dk: fix syntax error.
merged changes from branch my-registry
fix box url setting in Vagrantfile
remove all bin/start-* scripts, not used anymore
remove bin/push-images.sh, not used anymore
delete images/logstash and logstash-forwarder
fix typo in Vagrantfile
fixed some syntax error.
Merge pull request #2 from xueshanf/master

fixed some syntax error.
updated README.md with more information. Added bin/dk list to show available dockers.
Merge pull request #3 from xueshanf/master

updated README.md with more information. Added bin/dk list to show avail...
add local image tarballs to speed up vm bootstraping
remove the image tarball files
update the README.md
rename bin/.bash_profile to bin/bash_profile
resolving conflicts in README.md and bin/dk