Dynamic status indicator for parallel install

While the output of `cabal install` in the parallel case [was improved recently](https://gist.github.com/3032723), it can still be made better. As described in #440, we want to implement a dynamically-updated status indicator (similar to Gentoo's `emerge` UI) that would show the number of packages that are being processed, that are already installed and that have failed; possibly also their names.

If we opt to also use the dynamic status indicator for sequential install, we'll have to get rid of or modify the internal setup method since it doesn't support build logging.

One related issue that @dcoutts [mentions here](https://github.com/haskell/cabal/pull/964#issuecomment-6722293) is that printing of the last 10 lines of the build log for each failed package should be done during the post-install step (currently it's done in `executeInstallPlan`).