changed the opengraph meta data extraction to incorporate the html body.

[frostrot]

#192 Added the feature to incorporate all the meta tags outside of the html head, by changing in the function extract_items() in class openClassExtractor. Furthermore, added a test case to named opengraph_test_2 which uses the html of https://www.youtube.com/c/Freecodecamp where the meta tags are also present in the body of the html, and the function is able to correctly identify all the tags and parse it.

[lopuhin]

@frostrot also would you mind checking test failures? They look to be related to this PR.