Update start.html
New user screen CSS updates
LB-757 : Youtube's thumbnail became disproportionally larger on timeline

Fixed
Merge pull request #46 from nidzix/lb-757-youtube-responsive

LB 757 youtube responsive
LB-760 : Soundcloud's thumbnail became disproportionally larger on timeline

Fixed
Merge pull request #47 from nidzix/lb-760-soundcloud-frame

Quick CSS fix for soundcloud post
Update INSTALL.txt
LB-773: Help should link to most up-to-date manual

Updated help link.
LB-716 : Put Reopen/Close -> backend (REST part)
Merge remote-tracking branch 'sourcefabric/master' into devel
Merge remote-tracking branch 'sourcefabric/devel' into liveblog-15
Merge pull request #48 from eozan/LB-773

LB-773: Help should link to most up-to-date manual
Merge remote-tracking branch 'sourcefabric/devel' into liveblog-15