Only accepts dockerfile named Dockerfile

[Louise15926]

Current Behavior

If I name my dockerfile something other than 'Dockerfile' (say 'db.Dockerfile'), during app deploy it will give me this error: "unable to prepare context: context must be a directory".

$ ecs-preview app init --dockerfile "db.Dockerfile"
$ ecs-preview app deploy # throws error

Expected Behavior

Not throwing this error

[iamhopaul123]

Plus, if dockerfile path is not passed in by a flag then "pb.Dockerfile" cannot be recognized and listed when selecting which dockerfile to use.

But maybe this is expected because they can name their dockerfile to whatever name they'd like to use 🤷‍♂️