fakedynamo support for gsi

Hello @x-ma, 

Please review the following commits I made in branch 'giannic-fakedynamo-gsi'.

9b4deba56149bc6160aca1133ea551e01ffd49e5 (2014-03-03 11:19:57 -0800)
fakedynamo support for gsi

R=@x-ma