Relax dependencies for contracts
Relax dependencies for contracts

Middleman requires an older dependency for contracts
(https://github.com/middleman/middleman/blob/master/middleman-core/middleman-core.gemspec#L56)
than aruba. Using Aruba >=
1.0.0.pre.alpha.x with Middleman does not work. Relaxing the dependency
a bit helps to avoid that problem.

mvz/aruba,cucumber/aruba,mvz/aruba