Added a config file. Removed the old serv.list file. Added dinstall directory command line arguments.

Use our native Haskell tar implementation to extract code from tarballs. We now don't use an external tar program for anything.

Fix dependency parsing from the command line. Before it accepted partial parses, which for example made "cgi=3" parse as "cgi".

This required changing the PkgInfo type from an alias for GenericPackageDescription 
to a record with a Repo and a GenericPackageDescription.
ResolvedPackage and ResolvedDependency also had to be changed to
keep a Repo rather than a tarball URL.

Use the package-url field in the GenericPackageDescription to record the tarball url for each package.

This adds a dependency on zlib, to unzip the downloaded 00-index.tar.gz.
Once unzipped, a small pure haskell tar reader is used to read
the index contents.
Servers in the server list now have names which are used 
as local cache directory names.
The --with-server command line flag has been removed since it
did not allow specifying a server name.

This is very untested, but should make cabal-install able to resolve
dependencies again after the move to Cabal 1.2.0. The package descriptions
are stored in a very hacky format atm the moment.

Refactoring: add listInstalledPackages, and use that everywhere instead of getInstalledPackages with lots of arguments that all come from ConfigFlags.

Lemmih, Paolo Martini are the primary authors of cabal-install but were
missing from the list in LICENCE.

But it does not work yet as it need to be updated to take configurations into
account. At the moment it thinks no packages have any dependencies since
it does not finalise the configuration for the package.