sqlalchemy-type Biginteger cannot be handled as graphql-type integer because it is limited to 32 bit

[palmkevin]

According to the standard, the graphql-int-type is limited to 32 bit.
But BigInteger in sqlalchemy can contain greater numeric values...

I changed the converter in order to convert BigInteger to float instead of int and this seems to work without any drawback

[coveralls]

Coverage remained the same at 90.295% when pulling f83e406 on palmkevin:BigInteger into c07b746 on graphql-python:master.

[palmkevin]

Sorry for this messy pull request. I am new to git...
b8a4c8e does not belong to this request... how can I remove it? Edit: I figured it out myself

[coveralls]

Coverage remained the same at 90.295% when pulling b8a4c8e on palmkevin:BigInteger into c07b746 on graphql-python:master.

[coveralls]

Coverage remained the same at 90.295% when pulling 8b2fea5 on palmkevin:BigInteger into c07b746 on graphql-python:master.

[coveralls]

Coverage remained the same at 90.295% when pulling 8b2fea5 on palmkevin:BigInteger into c07b746 on graphql-python:master.

[coveralls]

Coverage remained the same at 90.295% when pulling 8b2fea5 on palmkevin:BigInteger into c07b746 on graphql-python:master.