Template improvements.

Improved agenda and participants overview.
Fixed merge error.
Fixed #703: Mcrophon icons for list of speakers
Fixed #702: list of speakers projetor/overlay style.
Fixed #701: Check bootstrap tooltips on all buttons.
Fixed #652: Button for ageda item with related sid.
Updated EN translation strings and updated EN po files.
Template fixes and improvements.
Updated DE translations.
Updated FR translations (Thanks to Moira).
Updated CHANGELOG.
Merge pull request #709 from emanuelschuetze/fixes-for-1.4b2

Fixes and improvements for 1.4b2