add readme and .style.yapf for formatting

crawler/.style.yapf

@@ -0,0 +1,21 @@
+[style]
+based_on_style = facebook
+
+# Formatting options
+column_limit = 88
+indent_width = 4
+use_tabs = false
+continuation_indent_width = 4
+
+# Spacing
+spaces_around_power_operator = true
+spaces_before_comment = 2
+
+# Splitting rules
+split_before_logical_operator = true
+split_before_bitwise_operator = true
+split_before_arithmetic_operator = true
+split_before_expression_after_opening_paren = true
+split_before_first_argument = false
+split_complex_comprehension = true
+allow_split_before_dict_value = true