Merge pull request #171 from Stiivi/master

[blog/new][l]: OLAP intro + model from @Stiivi.
Add tagline attribute to projects

Refs #161
Tidy up projects page js a little

Refs #162
Fix bug in 093b67c1 - repeated content in modals
Newsletter, 16 January
Merge pull request #172 from nmashton/master

Newsletter, 16 January
Fix bug in 093b67c1 - use data-filter
One more 093b67c1 bug.. concat filter string
[events][s]: add agenda calendar to sidebar of front page and join page.
[#73,events][s]: embed new google calendar on events page.
Merge branch 'master' of github.com:okfn/okfn.github.com
[hangouts][s]: update with latest hangout info.
Project filtering using chosen
[projects][s]: add froide as separate project and make featured.
[projects][xs]: fix formatting.
[projects][m]: update frictionless data and tweak layout a bit.
[projects][xs]: fix up slug for frictionless data.
[projects][s]: add elasticsearch.js to projects list - fixes #95.
[blog][s]: tweak old ElasticSearch post to mention elasticsearch library more.
[contact][s]: introduce newsletter list (sendy) and use as default for signup.