Some admin (Stack, gitignore)

[mheinzel]

Fixes for some small things I encountered when trying to setup and build the project.

1. When running stack build --fast --pedantic I got:

   WARNING: Ignoring out of range dependency (allow-newer enabled): universe-base-1.0.2.1. servant-docs requires: >=1.1.1 && <1.2
   

       /home/shared/projects/servant/servant-docs/src/Servant/Docs/Internal.hs:498:18: error:
       Not in scope: ‘U.cartesianProduct’
       Module ‘Data.Universe.Helpers’ does not export ‘cartesianProduct’.
       |
   498 |   gtoSamples _ = U.cartesianProduct render ps qs
       |                  ^^^^^^^^^^^^^^^^^^
   

   This happened because cartesianProduct was added in universe-base-1.1, which is not in the specified nightly-2018-09-28 snapshot.

2. When I tried running stack ghci servant-http-streams, I noticed it is not part of the stack.yaml (but of the cabal.project).

3. git picked up the tags file created by my editor.

Let me know if any of these are not wanted, I'm happy to amend the PR.

[mheinzel]

There seems to be problem with GHCJS in CI:

The following packages have unmet dependencies:

 ghcjs-8.4 : Depends: npm but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

I can try to find some time to see what is going on here, but maybe someone else knows.

edit: The same thing seems to be happening on other PRs like #1249.

[phadej]

this really should be part of your global gitignore. I'm against putting all editor temporary files into projects .gitignore.

Other stuff looks ok.

[phadej]

Cherry-picked parts in #1258.

Thanks!