migrate orgId for public data to 0

this will allow us to use uint encoding for org id's

fix #260

docs/http-api.md

@@ -35,7 +35,7 @@ POST /metrics/index.json
 
 * header `X-Org-Id` required
 
-Returns metrics stored under the given org, as well as public data under org -1 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
+Returns metrics stored under the given org, as well as public data under org 0 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
 
 #### Example
 
@@ -56,7 +56,7 @@ POST /metrics/find
 * format: json, treejson, completer, pickle, or msgpack. (defaults to json)
 * jsonp
 
-Returns metrics which match the query and are stored under the given org or are public data under org -1 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
+Returns metrics which match the query and are stored under the given org or are public data under org 0 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
 the completer format is for completion UI's such as graphite-web.
 json and treejson are the same.
 
@@ -112,7 +112,7 @@ POST /render
 
   If metrictank doesn't have a requested function, it always proxies to graphite, irrespective of this setting.
 
-Data queried for must be stored under the given org or be public data under org -1 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
+Data queried for must be stored under the given org or be public data under org 0 (see [multi-tenancy](https://github.com/grafana/metrictank/blob/master/docs/multi-tenancy.md))
 
 #### Example
 

docs/multi-tenancy.md

@@ -10,4 +10,4 @@ A metrictank based stack is multi-tenant. Here's how it works:
 * For a secure setup, you must make sure these headers cannot be specified by users. You may need to run something in front to set the header correctly after authentication
   (e.g. [tsdb-gw](https://github.com/raintank/tsdb-gw)
 * orgs can only see the data that lives under their org-id, and also public data
-* public data is stored under orgId -1 and is visible to everyone.
+* public data is stored under orgId 0 and is visible to everyone.

idx/idx.go

@@ -13,7 +13,7 @@ import (
 	schema "gopkg.in/raintank/schema.v1"
 )
 
-const OrgIdPublic = -1
+const OrgIdPublic = 0
 
 var (
 	BothBranchAndLeaf  = errors.New("node can't be both branch and leaf")