Added other allowed elements to sanitize()

The following html elements are now kept when sanitizing entries: aside, bdi, bdo, caption, col, colgroup, figure, figcaption, mark, ruby, rp, rt, samp, time. Most of them are new in HTML5. Based on the list at https://developer.mozilla.org/en-US/docs/HTML/HTML5/HTML5_element_list

I made this "patch" cause <figure> were stripped from a newspaper I read, and I added other missing elements on my way. In fact, I didn't know about most of them (<ruby> really?), looks like some are thought for asian languages (pronunciation hints).