Added containers to the Build-Depends list

I needed this to get it to build correctly in windows, using ghc version 7.6.3 installed with the haskell platform. Otherwise I would get an error:

    Finance\Quote\Yahoo.hs:82:18:
        Could not find module `Data.Map'
        It is a member of the hidden package `containers-0.5.0.0'.
        Perhaps you need to add `containers' to the build-depends in your .cabal file.
        Use -v to see a list of the files searched for.
    Failed to install Finance-Quote-Yahoo-0.8.0