osx-0.10.2: Make a .dmg installer

To simplify for people when they want to install Bubblemon we now have a .dmg
installer.

One of the steps to get around Apple's App Translocation / Gatekeeper Path
Randomization includes having the user copying files from one location to
another.

With this release, making that copy becomes part of the installation, enabling
us to shorten the installation instructions.