Update Travis CI config

[geerteltink]

• Removes irc notifications
• Removes slack notifications
• Removes hhvm
• Adds nightly PHP 7.2 builds
• Update to latest guidelines

[froschdesign]

@xtreamwayz
All these changes maybe fine, but no one can review your PR's, because where is the reference for this? Where can I read which changes are important, which changes should include or not and which file structure is preferred?
I do not mean the Travis documentation, I mean the requirements for all ZF repositories.

It can not be the goal, that only two or three people knows these requirements. Therefore we need a boilerplate for the Travis configuration file and the Composer file.

/cc @weierophinney

[geerteltink]

@froschdesign I agree. I've asked for sort of a template as well in the slack contributors channel yesterday.

For notifications: https://zendframework.slackarchive.io/contributors/page-4/ts-1499810981101710
hhmv drop was mentioned in a blog post I think.

[froschdesign]

@xtreamwayz
I know the blog post and I know the discussion on Slack, but this can not be a place for references or informations to contributors and maintainers.

• The blog is good to inform the "outside world".
• Slack and the forum is good for discussions, questions, etc.

But these channels are too fragmented and searching ends in a mess.

We already have a place for this kind of information:

Contributors and maintainers information for Zend Framework (https://github.com/zendframework/maintainers)

Now, we just have to use them!

[geerteltink]

For completeness:

• Add composer template maintainers#15
• Add travis template maintainers#16

[geerteltink]

@froschdesign Are these PR's good to merge now?