add flake8-checks to travis

src/escpos/cli.py

@@ -33,9 +33,11 @@ def str_to_bool(string):
     """
     return string.lower() in ('y', 'yes', '1', 'true')
 
+
 # A list of functions that work better with a newline to be sent after them.
 REQUIRES_NEWLINE = ('qr', 'barcode', 'text', 'block_text')
 
+
 # Used in demo method
 # Key: The name of escpos function and the argument passed on the CLI. Some
 #   manual translation is done in the case of barcodes_a -> barcode.
@@ -568,5 +570,6 @@ def demo(printer, **kwargs):
             command(**params)
         printer.cut()
 
+
 if __name__ == '__main__':
     main()

src/escpos/codepages.py

@@ -20,4 +20,5 @@ class CodePageManager:
     def get_encoding(self, encoding):
         return self.data[encoding]
 
+
 CodePages = CodePageManager(CAPABILITIES['encodings'])