Add user to bosh_sshers group (if it exists)
Add user to bosh_sshers group (if it exists)

[#117393755](https://www.pivotaltracker.com/story/show/117393755)

Signed-off-by: Dennis Leon <84f467a5e250ceeacb4292b28bf3ac3f822ea696@pivotal.io>

cmpz-engineering/os-conf-release,cmpz-engineering/os-conf-release