Pylinted a bit. Now just over 50% compliant.

gem/gemlang/__init__.py

gem/gemlang/ast/__init__.py

gem/gemlang/ast/ast_base.py

gem/gemlang/ast/ast_expression.py

gem/gemlang/ast/ast_statement.py

gem/gemlang/ast/parsetree2ast.py

gem/gemlang/ast/utils.py

gem/gemlang/model_generator.py

gem/model/edward2_extn.py

pylintrc