Some improvements I made

[stevefan1999-personal]

Well this is originally for #147, that since Hasura released its v1.3.0 it had beta support for Relay-styled query, so using ConnectionMode.EDGES almost worked out of the box! The problem is I cannot seem to totally refactor to support logical queries (AND, OR, EQ, GT, etc.), but most other things I found that are problematic were fixed to a certain degree, and although the test suite almost passes (what is that last one skipped suite), the coverage is drastically reduced to 94%. I haven't made more tests to the new changes too but I think it is not quite necessary.