about.md: add content

Add content regarding Aims, Governance, and How to Contribute. Text
provided by Amir and slightly modified by Ashish. Partially addresses
about.md: add table of contents
companies.md: add Hack to Facebook's description
Merge branch 'master' into about
about.md: add brief section on logos

Partially addresses #265.
mailing_lists.md: clean up titles

Make title reflect that page is about more than just mailing lists as
suggested in #357. Make titles less messy. Categorize into separate
sections.
mailing_lists.md: add Mantis bug tracker

As requested in #357.
mailing_lists.md: fix html title
capitalize titles consistently

Helps #368.
papers.md: improve and capitalize titles
papers.md: replace numbered lists with bulleted lists

Sequential numbers used were misleading. Markdown renumbered anyway and
many lists had just one item.
papers.md: add several talks and papers on industrial uses

Closes #311.
taste.md: change title to Code Examples

Also add links to other code example sites and pages. Closes #367.
Merge branch 'about'
mailing_lists.md: add French IRC channel
mailing_lists.md: add intro with info on other lists and forums
community/index.md: change link to mailing lists

Was to lists.ocaml.org, which only covers small set of all lists. Now
linking to main mailing lists page.
community/index.md: change Events to Meetings

Section links to Meetings page, and we refer to it as “meetings”
everywhere else.