The changelog for `servant` contains changes across core packages,
as we release them as a suite.
Also added links to the GitHub master as we might update entries
for old versions, as changelogs are written by humans.
- Add build-tool-depends, so new-build can use hspec-discover
- Add mtl bounds in tutorial (and dependency on mtl-compact)
- Add extra-source-files to tutorial, so it's buildable from sdist
This commit begins the reorganization of the servant-client project
so as to allow multiple backends, and also begins some much-needed
refactoring of the servant-client code.
