Update module google.golang.org/grpc to v1.38.0

See merge request !6

Update module github.com/prometheus/client_golang to v1.11.0

See merge request !9

Since the GRPC connection is provided externally, nothing can fail.

Update golang.org/x/net commit hash to d25e304

See merge request !4

Make it possible to apply an IP mask (different for v4 and v6) to all
addresses stored and retrieved from the database. This is transparent
to the API (you can still send and query individual IPs).

The default behavior becomes to aggregate away IPv6 addresses to a /64
network, while there is no change to IPv4 handling.

No need to duplicate functionality and have weird subset of
DialOptions available as part of the iprep client API.

Context was unnecessary when a simple internal channel will do. Also
fix queue_test.

Use a custom simpler format for records in leveldb, rather than
marshaling protobufs (2x speedup).

Add a streaming db.ScanAll method to retrieve all records grouped by
IP.

Use only two classifications, bruteforce / spam.