Fix for empty plans retrieval in demo

The BillingPlan.all() method seems to return just an empty dict, so the
code has been arranged to populate the plans list based on the
to_dict() methods.
Merge branch 'fsiddi-master'

Merge in no billing plan patch for subscription sample application
Update billing agg search transactions and travis build
Merge branch 'master' into stable

Merge in billing plan sample app update, transaction search update and travis build