Use consistent flipper namespace for dalli cache keys
Use consistent flipper namespace for dalli cache keys

This is to avoid any conflicts with other potential keys. General a good idea to always namespace based on function. The function here is flipper so this adds flipper/ before each key including the set of known features.

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