Add possibility to include and exclude arguments from generated cache key

[mgruner]

• Fixes Possibility to filter out arguments from path_cache_key #133

[mgruner]

@DmitryTsepelev can you have a look, please? The code doesn't exactly look nice, but I tried to keep changes minimal and according to the existing style. If this is the right direction then I can also try to add something to the README.md.

[DmitryTsepelev]

I like it a lot! Please proceed with docs and we'll merge it in

[mgruner]

@DmitryTsepelev documentation added.

When testing this with our actual use case in our software https://github.com/zammad/zammad, I found a bug in my initial code and also issues in the tests which caused some more changes, also to the tests to ensure that the use case really gets tested properly.

To me it looks good now, and it also works correctly in our use case. But please have another detailed look again if I got everything right. I took the cache_key: { exclude_arguments: … } syntax from your proposal. Is this the right signature that should get used in the gem?

If everything looks right to you, feel free to merge it, and please let us know when you plan to release a new version.

[mgruner]

@DmitryTsepelev sorry, rubocop corrected.

[DmitryTsepelev]

LGTM, I'll make a release right now

[mgruner]

Thank you!