Updates to harvard-university-of-the-west-of-england.csl

- Changed the access macro so that the URL or DOI are not shown for
electronic articles or books.
- Prefixed page numbers with pp.
- Removed the online macro for webpages.
- Other punctuation tweaks.

For examples see
http://www2.uwe.ac.uk/services/library/help/printable%20library%20guides
/9-uwe-harvard.pdf