Scrapy-loader-upkeep

Tidy up the code and added CI for code coverage.

Introduced new feature of parsers being named for better context (ref issue: 1)

Fixed bug in `get_css()` or `get_xpath()` since they're calling in `_get_cssvalues()` and `_get_xpathvalues()` respectively with the `field_name` variable but aren't accepting any `field_name` input, leading to errors.

First working prototype! 🎉