Add optional headers to purge call

[ddeboer]

Fix #117.

I think this makes sense, but @dbu, please validate whether this answers to a proper use case (#117).

[dbu]

we should also say that you should only use this when the header varies. if its always the same (e.g. a basic authentication or similar), you should just pass in a guzzle client configured to send that header, rather than spread the logic throughout the code.

[ddeboer]

Added a section to the docs.

[dbu]

i think its consistent to do this as we have it for refresh.

its a special case - the more common case of always having to send some headers (to authenticate or such) should be handled by passing a custom guzzle client.

[ddeboer]

Added doc section. As this doesn’t break BC – optional interface method arguments can be left out of implementations (nice one, PHP) – this can be safely merged.

[dbu]

are you sure? i thought php complains about that. but well, we are still RC so its like last moment ;-)

[dbu]

does the link really work like this? don't you need the filename in <>?

[stof]

@dbu it is a ref to the line 182 in this file.

[dbu]

thanks a lot!