'Current' symlink should point to actual .deb, .dmg, or .msi file

[jwir3]

The 'current' symlink points to the release directory right now. It should point to an actual file. So, instead, we should have a 'current' directory, with three symlinks, as follows:

• current/
  • deb -> current .deb release file
  • dmg -> current .dmg release file
  • exe/msi -> current .msi/.exe release file

This way, users don't have to know the actual version number in order to download the appropriate release.

[jwir3]

Hm, so this is a little tricky. If we want to deploy archives, this is probably the way to go, but if we want to deploy directories (as in #14), then we probably just want this to point to the current release directory. Perhaps we should add an option that specifies that archives are the intended deployment target?