Change the inplace package database to not use file-style database.

Instead we use HcPkg.init (e.g. ghc-pkg init). For ghc-pkg this will
create a new directory style db.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>
Signed-off-by: Duncan Coutts <duncan@well-typed.com>
Merge branch 'master' of git://git.haskell.org/packages/Cabal

Edward's patch to stop using old file style package dbs.
.travis.yml: Add GHC 7.2.2.
Add instance Binary LocalBuildInfo
Use Binary instance to save/restore dist/setup-config
Load binary LocalBuildInfo in package-tests

PackageTests has its own version of getPersistBuildConfig which does not
check which version of Cabal created dist/setup-config. Now that the
LocalBuildInfo is written with Binary, this version needed to be
updated, too.
Clarify Cabal dependencies policy

[ci-skip]
Merge pull request #2076 from ttuegel/binary-lbi

Use Binary to save/restore persistent build config