* move offer out of marketing package and remove marketing package
* fix imports
* fix rename errors
* remove offer service
* change package name from offers to rewards
* fix linting
* remove unused code and use appropriate comment
* add voucher service on storage node
* config field tag syntax, go routines for requests
* hook up voucher service in storagenode/peer.go
* add voucher config to testplanet
* add voucher config to testplanet
* add voucher response status INVALID, ACCEPTED, REJECTED
* add a test for vouchers service
* handle no row from GetValid, test it
* add trust pool to voucher service
* use trusted list to get satellites
* verify vouchers upon receipt
* test VerifyVoucher
* pkg/audit: Add DQ test for too many failed audits
Add an integration test which checks that a node which fails several
audits gets disqualified but not before it reaches the audit reputation
disqualification cut-off.
* internal/testplanet: Set DQ cut-off config values
Set the values of the Overlay cache DQ cut-off configuration parameters
used by testplanet.
