Non-fetcheable remote files

[MrHedmad]

There might be some cases where a pipeline fetches data in a non-trivial way, and therefore Kerblam! cannot handle it with a get request. In these cases it might be useful to specify extra remote files so that we can cleanup and pack correctly.

E.g. In the kerblam.toml:

[data.remote]
"extra" = ["file_1", "file_two"]

Allowing regex patterns in such cases (maybe with a specific syntax, like /some_regex/) might also be useful.

[MrHedmad]

Fixed in PR #113