Improved link_dotfiles to allow multiple dotfiles in platform specific folder

Signed-off-by: Michael Welter <michael@cetoncorp.com>
Renamed link_dotfiles to setupenv as more appropriate now

Signed-off-by: Michael Welter <michael@cetoncorp.com>
Moved creation of subl symlink to setupenv rather than havee it run each new shell

Signed-off-by: Michael Welter <michael@cetoncorp.com>