Add stack support

[NCrashed]

Hi! Thank you for awesome library!

The package isn't buildable with stack either current stable image lts-3.2, either latest nightly nightly-2015-08-27.

stack.yml:

flags: {}
packages:
- '.'
extra-deps:
  - geojson-1.3.0
  - validation-0.5.1
resolver: nightly-2015-08-27

--  Failure when adding dependencies:    
      aeson: needed (==0.9.*), latest is 0.9.0.1, but 0.8.0.2 found
      lens: needed (==4.11.*), latest is 4.12.3, but 4.12.3 found
    needed for package: geojson-1.3.0

--  Failure when adding dependencies:    
      geojson: needed (-any), latest is 1.3.0, but couldn't resolve its dependencies
    needed for package: new-template-0.1.0.0

Are there any plans to publish the library to stackage or relax version bounds to fit LTS?

[domdere]

There were no explicit plans to publish the library to stackage since i dont really use it,

Not averse to the idea putting it up there though.

I would be pretty reliant on ppl like yourself to speak up when compatibility is broken though cos I'll probably never notice.

Thanks for the PR, dont really have a problem with relaxing the version bounds, as long as upper bounds do exist.

[NCrashed]

Not averse to the idea putting it up there though.

The major problem for publishing at stack is validation dependency. As soon as the library is at stackage the geojson also could be published. I'll check out validation for the case.

I would be pretty reliant on ppl like yourself to speak up when compatibility is broken though cos I'll probably never notice.

Never mind, I always whine to an issue tracker when face build problems.

[newmana]

The fix for the validation was fixed in 1.3.3.

http://hackage.haskell.org/package/geojson

And now part of the nightly builds: https://www.stackage.org/nightly-2018-09-20/package/geojson-1.3.3