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
Merge pull request #131 from pictuga/patch-1

Added other allowed elements to sanitize()