Turning off IPv6 causes the tests to fail because the Go
`net.Listen()` function obtains a `[::]` address when using
a `localhost:0` bind address. Looking through the Go source
code, I don't see a good way to fix that.
This change adds a test flag to allow users to specify the
network name when running the test:
```sh
go test github.com/pilosa/pilosa/server -network tcp4
```
This mainly involved running `RecalculateCache()` on all fragments
in `TopN` tests. It seems these tests have been running as LRU
caches, and once we made `ranked` the default, they stopped working.
Some tests were affected by the change in partition number and
therefore the change in fragment to node mapping.
this affects the scanner/parser and makes it produce signed ints rather than
uints, and so it affects all code that is expecting unsighed ints to come out of
the parser.
