x/ref: Update package doc for all packages.

This brings all our package doc into a reasonable and consistent
state.  To see what it looks like, visit:

http://toddw-linux.mtv.corp.google.com:6060/pkg/v.io/

Note that services/agent is the only remaining package without
reasonable docs.  I will update the docs separately, since I
still need to restructure some of its packages.

Change-Id: Id8bc737e3566a0ef3ab110e1245ad30ce1aac121
diff --git a/test/doc.go b/test/doc.go
index f0fbcdb..cb84f2b 100644
--- a/test/doc.go
+++ b/test/doc.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package test provides initalization for unit and integration tests.
+// Package test implements initalization for unit and integration tests.
 //
 // Init configures logging, random number generators and other global state.
 // Typical usage in _test.go files: