Add simple csv importer client

This creates a List of Maps where the first row in the CVS file is used
to determine the key names.

Fixes #29

clients/csv_importer/.gitignore

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+csv_importer

clients/csv_importer/README.md

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+# CSV Importer
+
+Imports a CSV file as a List of Maps where the first row of the CSV file
+describes the keys of the Map.
+
+## Usage
+
+To import a CSV file do:
+
+```
+$ go build csv_importer.go
+$ ./csv_importer -file-store="/tmp/foo" <URL>
+```
+
+## List of CSV URLs
+ - https://data.cityofnewyork.us/api/views/kku6-nxdu/rows.csv?accessType=DOWNLOAD

clients/csv_importer/csv_importer.go

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+package main
+
+import (
+	"encoding/csv"
+	"flag"
+	"io"
+	"log"
+	"net/http"
+
+	"github.com/attic-labs/noms/chunks"
+	"github.com/attic-labs/noms/datas"
+	"github.com/attic-labs/noms/types"
+)
+
+func main() {
+	flags := chunks.NewFlags()
+	flag.Parse()
+	cs := flags.CreateStore()
+	if cs == nil {
+		flag.Usage()
+		return
+	}
+
+	url := flag.Arg(0)
+	if url == "" {
+		flag.Usage()
+		return
+	}
+
+	res, err := http.Get(url)
+	defer res.Body.Close()
+	if err != nil {
+		log.Fatalf("Error fetching %s: %+v\n", url, err)
+	} else if res.StatusCode != 200 {
+		log.Fatalf("Error fetching %s: %s\n", url, res.Status)
+	}
+
+	r := csv.NewReader(res.Body)
+	r.FieldsPerRecord = 0 // Let first row determine the number of fields.
+
+	keys, err := r.Read()
+	if err != nil {
+		log.Fatalln("Error decoding CSV: ", err)
+	}
+
+	value := types.NewList()
+	for {
+		row, err := r.Read()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			log.Fatalln("Error decoding CSV: ", err)
+		}
+
+		m := types.NewMap()
+		for i, v := range row {
+			m = m.Set(types.NewString(keys[i]), types.NewString(v))
+		}
+		value = value.Append(m)
+	}
+
+	ds := datas.NewDataStore(cs)
+	roots := ds.Roots()
+
+	ds.Commit(datas.NewRootSet().Insert(
+		datas.NewRoot().SetParents(
+			roots.NomsValue()).SetValue(
+			value)))
+}