Remove assumption that the table of contents will be an <ol>.

A recent change to anolis[1] caused it to output the table of contents
using <ul> tags instead of <ol> tags, breaking the generation of the
table of contents for individual pages.

Instead, we search for <ul> or <ol> tags.

[1] https://bitbucket.org/ms2ger/anolis/commits/62d9a108439d70e33ad2bb3b4009efd3dbf9cac5
Merge pull request #1 from Osmose/fix-ol-assumption

Remove assumption that the table of contents will be an <ol>.