* 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
* add last_ip field to dbx model node, generate dbx
* add last_ip to node proto, generate pb
* migrate
* resolve address in transport.DialNode, update lastIp in cache.UpdateAddress
* use net.SplitHostPort to isolate host address from port
* define DistinctIPs flag
* add test for GetIP
* select last_ip when querying for nodes
* if distinctIPs flag == true, query for nodes with distinct IPs
* some basic tests
* change last_ip to field 14 in proto
* remove comments
* check err
* change distinctIPs to distinctIP
* exclude IPs from newNodes in query for reputable nodes
* add index on last_ip
* only add to excludedIPs if flag is true
* test half new nodes returns distinct IPs
* fix alignment
* add test
* rework ip filter query, add retry logic, add switch for database driver
* add retry to SelectNewNodes
* change discovery intervals so IPs don't get overwritten
* remove TestGetIP
* edit updating node stats in test
* split exclude into nodeIDs and IPs
* separate non-distinct IP query into other function
* trigger checks
* remove else block
