Add fixtures build tag to all fixtures.go files

Ensure testing dependencies from fixtures don't leak into builds.
diff --git a/rackspace/lb/v1/acl/fixtures.go b/rackspace/lb/v1/acl/fixtures.go
index e3c941c..6761b9f 100644
--- a/rackspace/lb/v1/acl/fixtures.go
+++ b/rackspace/lb/v1/acl/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package acl
 
 import (
diff --git a/rackspace/lb/v1/lbs/fixtures.go b/rackspace/lb/v1/lbs/fixtures.go
index 6325310..a002c67 100644
--- a/rackspace/lb/v1/lbs/fixtures.go
+++ b/rackspace/lb/v1/lbs/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package lbs
 
 import (
diff --git a/rackspace/lb/v1/monitors/fixtures.go b/rackspace/lb/v1/monitors/fixtures.go
index a565abc..72bfdcd 100644
--- a/rackspace/lb/v1/monitors/fixtures.go
+++ b/rackspace/lb/v1/monitors/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package monitors
 
 import (
diff --git a/rackspace/lb/v1/nodes/fixtures.go b/rackspace/lb/v1/nodes/fixtures.go
index 8899fc5..350eefa 100644
--- a/rackspace/lb/v1/nodes/fixtures.go
+++ b/rackspace/lb/v1/nodes/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package nodes
 
 import (
diff --git a/rackspace/lb/v1/sessions/fixtures.go b/rackspace/lb/v1/sessions/fixtures.go
index 077ef04..e59dd6c 100644
--- a/rackspace/lb/v1/sessions/fixtures.go
+++ b/rackspace/lb/v1/sessions/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package sessions
 
 import (
diff --git a/rackspace/lb/v1/ssl/fixtures.go b/rackspace/lb/v1/ssl/fixtures.go
index 5a52962..d03d6de 100644
--- a/rackspace/lb/v1/ssl/fixtures.go
+++ b/rackspace/lb/v1/ssl/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package ssl
 
 import (
diff --git a/rackspace/lb/v1/throttle/fixtures.go b/rackspace/lb/v1/throttle/fixtures.go
index f3e49fa..61e601c 100644
--- a/rackspace/lb/v1/throttle/fixtures.go
+++ b/rackspace/lb/v1/throttle/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package throttle
 
 import (
diff --git a/rackspace/lb/v1/vips/fixtures.go b/rackspace/lb/v1/vips/fixtures.go
index 158759f..080e617 100644
--- a/rackspace/lb/v1/vips/fixtures.go
+++ b/rackspace/lb/v1/vips/fixtures.go
@@ -1,3 +1,5 @@
+// +build fixtures
+
 package vips
 
 import (