set blob content from given text in StorageBlobModel instance. Parameters are:
        - text (required): path to a local file 
        - encoding (optional): text encoding (default is utf-8)
        - mimetype (optional): set a mimetype. azurestoragewrap will guess it if not given

def fromtext(self, text, encoding='utf-8', mimetype='text/plain'):
        """ 
        set blob content from given text in StorageBlobModel instance. Parameters are:
        - text (required): path to a local file 
        - encoding (optional): text encoding (default is utf-8)
        - mimetype (optional): set a mimetype. azurestoragewrap will guess it if not given 
        """
        if isinstance(text, str):
            text = text.encode(encoding, 'ignore')

            # Load text into self.__content__
            self.content = bytes(text)

            self.properties.content_settings = ContentSettings(content_type=mimetype, content_encoding=encoding)

        else:
            raise AzureStorageWrapException(self, 'Can not load blob content, because given text is not from type string')