Fix the TV section that i broke with 683684c7

This fixes issue #57
XBMC expects rating to be a number not a string.

This is preventing changes from being saved as well. (#57)
Fix the mark (un)watched in the TV section.

This fixes issue #58.
Fix typo in README.md - XWMM not X V MM
Merge pull request #74 from fyfe/fix-issue-74

Fix typo
Merge pull request #63 from fyfe/fix-issue-57

Fix #57 Tvshow update doesnt work.
Merge pull request #64 from fyfe/fix-issue-58

fix #58  TV show - Mark as watched/unwatched has no effect
Update change log and bump version number.
Merge pull request #75 from fyfe/update-changelog

Update change log and bump version number.
The files section is broken beyond repair, and XBMC's API doesn't support anything
that would make this section useful.

(Issue #43)
Remove unused XBMCScanContent function from include/xbmc.js
Remove scraper artwork as it's no longer used.
Remove unused tree grid extension.
Update change log for issue #65.