Fix config name inconsistency

[josedonizetti]

This PR renames configuration from 3 different notifiers to make it consistent with others. Basically, global configurations will be named <notifier>_api_url, and local configurations per notifier api_url.

This are breaking changes.

Fixes #680 and #875

@stuartnelson3 @brancz @brian-brazil @juliusv

[brian-brazil]

We've generally followed the name that the provider uses in their docs when it comes to these things, as a user cares about only 1 of these which they already know - not that they're consistent across the alertmanager.

Do these all match up with that?

[brancz]

I wonder how much it's worth breaking these, as I'm pretty sure a lot of configurations are going to break when people upgrade to these changes.

[josedonizetti]

@brian-brazil I've changed the PR to rename only two configs:

• hipchat_url to hipchat_api_url, this fixes hipchat_url is not consistent with api_url #875 and checking the hipchat documentation the term 'API' does match more than just 'URL'

• opsgenie_api_host to opsgenie_api_url, this fixes opsgenie_api_host in the config should be opsgenie_api_url #680, the opsgenie documentation does use the terms 'API' and 'URL'

[josedonizetti]

@brancz Yup, agree that it might not be worth. My idea when I first sent this PR was to have it merged for the version 0.10.0, was considering at the time that the first double number in the version would be a good moment to such a break.

But I totally understand if you think that is not worth, let's just add a note about it on the issues so no other PR is created for it, for now, maybe in a future 1.0 release the break might make more sense.

[brancz]

in a future 1.0 release

I think this would be more appropriate. Similar breaking re-namings were done from Prometheus 0.x to 1.x.

[brian-brazil]

I don't think that this is a breaking change in practice, as these settings should ~never need to be changed from the defaults by users.

[stuartnelson3]

As brian said, these values shouldn't be modified by the users. I'll make a note of it in the next release, though.

[aecolley]

You lose a karma point for this because my employer's private HipChat server means that this was a setting that most definitely needed to be different from the default.

[stuartnelson3]

Thank you for bringing that to my attention. I was not aware hipchat could be run privately.