capture stack traces in dynamite errors

Hello @x-ma, @sboora, 

Please review the following commits I made in branch 'nick-capture'.

1eb16e6197852b53a564be7d826d4cdc5b1f2baa (2014-12-03 18:46:05 -0500)
capture stack traces in dynamite errors

R=@x-ma
R=@sboora