Freeze formatio dependency to 1.1.1 to allow tests to continue working

formation 1.1.2 introduces "(empty string)" as special formatting of
empty strings, which is a breaking change and should really be 1.2.0

However, right now we just need to have the tests passing so people
can keep working on **this** codebase.
Merge pull request #626 from mroderick/freeze-formatio-dependency

Freeze formatio dependency to 1.1.1 to allow tests to continue working