Add regression test for escaping feature names
Add regression test for escaping feature names

* 7151715c6afd55b3b87b46aada152dff3fc13ea9 was merged which escapes
feature_names like we were doing before the change to support slashes
and adding the FeatureNameFromRoute module for pulling the feature name
out of the request.  This adds a regression spec to make sure this
continues to work in the future as changes are made.

jnunemaker/flipper,jnunemaker/flipper,jnunemaker/flipper,jnunemaker/flipper