Allow text 1.0 and 1.1

Package text-1.0.0.0 is already out, so allow that.  Also assume that
the next text version won't break things either, so allow text-1.1
too.

Tested on a local cabal sandbox by running unit tests.

Fixes #38
Merge pull request #39 from nurpax/text-1.0

Allow text 1.0 and 1.1