Test writable loader with apache config files

[sydneyli]

Depends on #73. Check out the last two commits for the full diff.

In Certbot, we have a lot of sample config files that we test against. Here's a bunch from issues in the past: https://github.com/certbot/certbot/tree/5b45d0742ad51bb9ad93dd61977b5b2d4bcc4319/certbot-apache/certbot_apache/tests/apache-conf-files

And we also test against the default system apache configurations on different OSes: https://github.com/certbot/certbot/tree/5b45d0742ad51bb9ad93dd61977b5b2d4bcc4319/certbot-apache/certbot_apache/tests/testdata

I started testing apacheconfig against these files-- it might be good to check in a bunch of these files, to prevent future regressions. Let me know what you think.

This is a draft pull request for now! Going to add some more test configs.

EDIT: Woah! this is a huge diff. Most of it is just really long config files. The only piece of code added in this PR should be a new integration test at tests/integration/test_apache_samples.py.

[codecov-io]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@27845ec). Click here to learn what that means. The diff coverage is 31.2%.

@@            Coverage Diff            @@
##             master      #74   +/-   ##
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  Files             ?        7           
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  Hits              ?      619           
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Impacted Files	Coverage Δ
apacheconfig/__init__.py	100% <100%> (ø)
apacheconfig/wloader.py	29.5% <29.5%> (ø)

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[sydneyli]

If you anticipate maintaining a large collection of sample files, may be it would make sense to push them all into a separate package just for testing (e.g. apacheconfig-tests)...?

Yeah, we chatted about this briefly as well (breaking out our test files from Certbot). For the time being, I think this is alright, but if we find ourselves updating this set of files frequently, it would definitely make more sense to pull it out into an independent testing package that both Certbot and apacheconfig can depend on.