Setup script

Improvements:
* Only run if dot files symlink not found
* Only run if dot files installed to correct location
* Only symlink dotfiles-local if it exists
* Move RDM connections out of post-up hook
Update Brewfile

ZSH is installed as part of the laptop script, as is RCM.
Add update

Allows anytime updating of dot files.
* Checks origin/master for updates
* Checks to see if dotfiles-local symlink exists, if not creates it,
but only if the folder exists in Dropbox
* Runs rcup to update.
Update README