[hab] Add `install.sh` script as placeholder.
[hab] Add `install.sh` script as placeholder.

This is a direct copy of `components/studio/install.sh` except for the
last line, which is the entire "install Studio" behavior :)

It does seem silly to have 2 install scripts doing 99% the same thing,
but chances are that the Studio `install.sh` will eventually be removed
as `hab` will perform an install-on-demand when it is called for.

Signed-off-by: Fletcher Nichol <fnichol@nichol.ca>

Pull request: #556
Approved by: reset

habitat-sh/habitat,nathenharvey/habitat,nathenharvey/habitat,habitat-sh/habitat,rsertelon/habitat,georgemarshall/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,georgemarshall/habitat,georgemarshall/habitat,rsertelon/habitat,georgemarshall/habitat,nathenharvey/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,georgemarshall/habitat,georgemarshall/habitat,nathenharvey/habitat,georgemarshall/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,nathenharvey/habitat,nathenharvey/habitat,georgemarshall/habitat,habitat-sh/habitat,rsertelon/habitat