This PR adds the ability to import field values into RangeEnabled frames
using the `pilosa import` command.
Example:
```
pilosa import -i i -f f --field foo sample-vals.csv
```
imports data from sample-vals.csv, which contains data in the format:
```
[ColumnID, Value]
```
Also fixes a bug where `frame.rangeEnabled` was not being set on frame creation.
This was populated by the `time_granularity` query argument, but that isn't being used either.
I believe this is left over from an early version of Pilosa prior to `Range()` query support.
Because the *pb.go files get auto-generated, we can't easily
keep the license block on the top of the *.pb.go files.
Instead, we keep a copy of the LICENSE file in the same directory
as the generated *.pb.go files.
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.
Previously the cache type (`lru` or `ranked`) was determined by
checking the ending suffix of the frame. If it ended with a `.n`
then it was ranked. Otherwise it was an LRU.
This commit changes frames so that a `cacheType` option can be
passed in during creation to set either `lru` or `ranked`.
