Merge pull request #252 from rodrigopinto/master

Add some proposals.
Berlin 2013: Add Engine Yard as sponsor.
Merge pull request #253 from jbraeuer/master

Berlin 2013: 1 gold sponsor.
DoDu 2013: adding Andrew Clay Shafer talk proposal 'There is no talent shortage'
DoDu 2013: hopefully fixing the bullet point list in Andrew's presentation
DoDu 2013: now hopefully fixing the link in Andrew's presentation
DoDu 2013: Oops that version of the presentation was not meant to be published
Update _sponsors.txt

Changed the ImmobilienScout24 sponsoring URL
Merge pull request #254 from IngmarKrusch/master

Berlin Sponsor update
change sponsor from citrix to cloudstack
Berlin 2013: Update program.
Adjust to reality.
Berlin 2013: Add Tarent AG as silver sponsor.
added thanks to AFS for Austin
Merge pull request #255 from drozer/master

apache cloudstack approved the sponsor
Merge pull request #257 from jbraeuer/master

Berlin 2013: Almost final program. Add silver sponsor Targent.
Finalize program.
Update proposals - 2 talks are ignites now.
updated cloudstack url
Merge pull request #258 from jbraeuer/master

Berlin 2013: Final program.