build_chroot: for wheezy install base64-bytestring via cabal
build_chroot: for wheezy install base64-bytestring via cabal

The version packaged in debian wheezy is less than the minimally
required version 1.0.0.0.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Helga Velroyen <2d0126b1ec6f9ec5cbec4a7012aa14faeaef10f5@google.com>

onponomarev/ganeti,dimara/ganeti,onponomarev/ganeti,dimara/ganeti,andir/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,apyrgio/ganeti,grnet/snf-ganeti,leshchevds/ganeti,apyrgio/ganeti,mbakke/ganeti,yiannist/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,yiannist/ganeti,mbakke/ganeti,andir/ganeti,bitemyapp/ganeti,bitemyapp/ganeti,yiannist/ganeti,andir/ganeti,grnet/snf-ganeti