JuliaLang/julia — pull request #7924 by timholy (2014-08-08 22:36:42+00:00)
Title: Add Pkg.whorequires to list packages depending on a particular package

Do not merge until the 0.4 window opens.

Demo:
```
julia> Pkg.whorequires("Color")
8-element Array{String,1}:
"Cairo"
"Compose"
"Gadfly"
"Images"
"ImageView"
"ProfileView"
"PyPlot"
"Winston"
```

Now I know which packages should be tested if I'm contemplating a breaking change to Color.

CC @StefanKarpinski.