Support remote shell override for rsync

[sohoffice]

rsync can benefit from an alternative remote shell, like for example using a control master ssh connection.

We should allow user to specify remoteShell under profiles > connection. This will be used as the -e parameter when invoking rsync. For example:

rsync -av -e '{{remoteShell}}' --exclude-from=.piaasignore --delete --copy-links . [email protected]:~/src

Control Master SSH Scenario:

1. We could have opened a control master connection with ssh -nNf -o ControlMaster=yes -o ControlPath="$HOME/.ssh/.control-%L-%r@%h:%p" user@host
2. Specify remoteShell as ssh -o 'ControlPath=$HOME/.ssh/control-%L-%r@%h:%p'
3. The control master connection can be terminated with ssh -O exit -o ControlPath="$HOME/.ssh/.control-%L-%r@%h:%p" user@host