Update sshd.sh

Update to prevent centos and redhat delay during login of around 20 seconds on initial startup.   Does not happen if you already have the GSSAPI infrastructure setup correctly but most folks don't, and those who do will be able to re-configure this easily.  In other words, GSSAPI disabled by default.
Update to packer 0.5.1

packer fix on packer/*.json
0.4.1=>0.5.1 in .travis.yml
Merge pull request #150 from sc0ttruss/patch-1

Update sshd.sh
Merge pull request #152 from lwieske/master

Update to packer 0.5.1