Add skip and include directive in introspection schema

[leszekhanusz]

Workaround for issue #278 until graphql-js#3419 has been fixed.

Always adding skip and include default directives in schema built from introspection.

[codecov-commenter]

Codecov Report

Merging #279 (d9b85de) into master (2be6aaa) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #279   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           22        23    +1     
  Lines         1800      1815   +15     
=========================================
+ Hits          1800      1815   +15     

Impacted Files	Coverage Δ
gql/client.py	100.00% <100.00%> (ø)
gql/utilities/__init__.py	100.00% <100.00%> (ø)
gql/utilities/build_client_schema.py	100.00% <100.00%> (ø)

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[Cito]

I agree that's the cleanest workaround, @leszekhanusz. Strictly speaking there are two more directives (deprecated and specifiedBy, the latter maybe only since GraphQL-core 3.2).

[leszekhanusz]

I agree that's the cleanest workaround, @leszekhanusz. Strictly speaking there are two more directives (deprecated and specifiedBy, the latter maybe only since GraphQL-core 3.2).

Yes I know but deprecated and specifiedBy are directives for the schema. I don't think they make sense inside a query.
As we are only validating queries in gql I think it could be enough.

[Cito]

Right, that makes sense.