Custom Output Name in CircleCI

[balanced-Chris]

Allow for the definition of a custom output name for the compressed file artifact. Allow for variables to used in that name as well.

To explain, the goal of the process is to eventually have all successful builds on the master branch upload automatically to a github release AND a cloud storage folder. For the last to happen the filename would need to be unique. While the workaround to put each file in a uniquely named folder would work it just creates another level of file nesting that is unneeded.

[webbertakken]

These are great suggestions!

I'm moving them to the relevant repository.