Bump authcode sample app to spring boot 1.5.5
Bump authcode sample app to spring boot 1.5.5

[finishes #148928881] https://www.pivotaltracker.com/story/show/148928881

Signed-off-by: Hieu Nguyen <56c9db28458cd1d2479acf4d8976573d3d9b5d2b@students.olin.edu>

tnwang/identity-sample-apps,tnwang/identity-sample-apps,tnwang/identity-sample-apps