Merge remote-tracking branch 'upstream/master'
Removed duplicate word "first"
Merge pull request #530 from LuqiPan/patch-1

Removed duplicate word "first"
Add links to videos for OUD2014
Merge remote-tracking branch 'upstream/master'
add links to slides
also add html files from media
Merge pull request #531 from garrigue/master

Add slides for OCaml 2014
Add a more visible link to the meeting page
Update the meeting page
add Xavier's slides
Merge pull request #533 from garrigue/master

add Xavier's slides
add Jun Furuse's slides
Merge pull request #535 from garrigue/master

Add Jun Furuse's slides
Improve the install page, fix some typos.
Merge pull request #536 from dmbaturin/master

Improve the install page, fix some typos.
add Arthur Chargueraud's slides
Merge remote-tracking branch 'upstream/master'
Merge pull request #537 from garrigue/master

add Arthur Chargueraud's slides
install.md: move sentence about OPAM

Introductory sentence about what OPAM is was awkwardly in 3rd
paragraph. Moved to be the first sentence.