Probe firmware version 4500

• RIPE Atlas probe software now supports two more architectures: TP-Link (for the next generation probes) and CentOS (for RIPE Atlas anchors).
• There is now support for one-off measurements for ping, traceroute, DNS, and HTTPget.
• We fixed a bug in DNS measurements in which, when querying local resolvers, more queries went to the last resolver.
• Fixed "error" : { "TUCONNECT" : "Success"}. Before this version DNS TCP and HTTPget reported an error message "Success".
• First release of anchor package