* filter schema identifiers to conform to graphql naming scheme,closes #134
Filter out tables, columns, relationships etc which does not conform to
graphql naming scheme.
This ensures GraphiQL initialisation works properly for existing
databases.
* rename `isGraphQLConform` to `isValidName`
* rename all graphQL validators
* server: basic test setup
* server: use the default transaction mode
* server: basic tests in yaml files
* server: restructure test setup and some more tests