Poll - Close/Open Button translation

Not yet in transifex, update manually.
Update onebox gem for image fixes
FIX: Extra `&` character
Add script/pull_translations. It pulls translations from Transifex, and does some post-processing on the files.
Update translations from Transifex
Don't look for a JS format. IE11 seems to not request it even with a
`<script>` tag.
Merge pull request #2264 from Onaldanm/patch-2

Poll - Close/Open Button translation
FIX: give an accurate reason why a user's posts can be deleted from admin
Exclude category definition topics from similar search
Merge branch 'master' of https://github.com/discourse/discourse
Merge branch 'master' of github.com:rux-pizza/discourse