Invalidate output cache using POST

[Cyclonecode]

Related issues

#2083

Short description and why it's useful

As described in the feature request, clearing the output cache should be supported by using either POST or GET requests. Since both GET and POST request now clears the cache in the same way it might be better to move the clear cache thing into a separate function?

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[pkarw]

Please apply the DRY principle and extract the request handler for cache invalidation as a function to be called in the .post and .get handlers you can also use .all handler for all request method however we probably need to support just get and post in here

[Cyclonecode]

@pkarw - Yes I also thought this would be nice. Wrote a comment about this in the PR =) I will fix this today.

[pkarw]

It will be a little bit nicer:
app.post(‘/invalidate’, invalidateCache)
app.get(‘/invalidate’, invslidsteCache)

[Cyclonecode]

Haha, I actually did this already but forgot to push =) I will do this now.