Deal with raw HTML snippets post pandoc conversion

[peterjc]

There are some HTML snippets left in the post conversion markdown. These need to be reviewed and addressed individually.

e.g. the main page used HTML for the blue donation box layout, with mediawiki text within it. This resulted in Markdown within an HTML block which does not render as expected. This might be best resolved by turning the contents of the blue box into HTML too? Done in 994f421

[peterjc]

e.g. Logos on https://github.com/OBF/wiki/edit/main/BOSC_2014.md ~ https://obf.github.io/wiki/BOSC_2015

[peterjc]

With the progress on #10 the logo tables were looking much better, they just needed their borders turned off. I've not spotted any other raw HTML issues.

These attempts failed - note we do not want hide the borders in the actual tables in the BOSC schedule pages, just the layout tables for image placement:

$ sed -i 's#<table border="0">#<table style="border: none !important;">#g' BOSC_????.md BOSC_????_Panel.md Codefest_*.md

$ sed -i 's#<table>#<table border="0">#g' BOSC_????.md BOSC_????_Panel.md Codefest_*.md

[peterjc]

Looks like we'd need to override this at the level, or tweak the theme - quoting https://github.com/pages-themes/cayman/blob/master/_sass/jekyll-theme-cayman.scss

  table {
    display: block;
    width: 100%;
    overflow: auto;
    word-break: normal;
    word-break: keep-all; // For Firefox to horizontally scroll wider tables.
    -webkit-overflow-scrolling: touch;

    th {
      font-weight: bold;
    }

    th,
    td {
      padding: 0.5rem 1rem;
      border: 1px solid $table-border-color;
    }
  }

e.g. Set $table-border-color to the page background?

[peterjc]

Transparent worked, although it might now be worth forcing a border on the schedule pages, e.g. https://obf.github.io/wiki/BOSC_2017_Schedule