Uninstall curl before running debian-bootstrap

debian-bootstrap attempts to install cabal-install-1.16, which can
either work with curl, wget, or fetch, in that order of preference.
Unfortunately the hackage URLs have changed since 1.16 and with the
arguments used in cabal-install's bootstrap script, curl doesn't
follow 301 redirects.

The simplest solution is to uninstall curl, so that wget is used
instead.
Remove packages for #295
Upgrade to cabal-install-1.18 instead

Instead of removing curl to work around limitations in the
cabal-install-1.16 bootstrap script, we upgrade to cabal-install-1.18
instead.
Merge pull request #294 from gelisam/no-curl

Uninstall curl before running debian-bootstrap
Added monad-journal.
Merge pull request #296 from phaazon/master

Added monad-journal.
Add back some libraries
Add shell-conduit (discussed with @chrisdone)
Add retry
isomorphism/these#11
Soostone/retry#15
Turn on old-locale flag
Add ghc-syb-utils
Add Tom Streller's yesod-auth-oauth2

https://hackage.haskell.org/package/yesod-auth-oauth2
Make myself the maintainer of yesod-auth-oauth2
Merge pull request #298 from benekastah/patch-1

Add Tom Streller's yesod-auth-oauth2
Temporarily disabled yesod-auth-oauth2 due to #299
Add monadcryptorandom
Add yesod-auth-hashdb
Merge pull request #300 from paul-rouse/master

Add yesod-auth-hashdb