"veyron/runtimes/google/security": Add persistence to PublicIDStore

This CL modifies the NewPublicIDStore factory function to create
PublicIDStore that persists all updates to the provided directory.
Additionally it modifies rt.Init() to create a persisting-PublicIDStore
if a directory location is provided via the VEYRON_PUBLICID_STORE env
variable.

Change-Id: I154e1040536fd5fd2be0354e1417013ddb9e741c
9 files changed
tree: 1262203666c64b9134462f23eb840723be64de3d
  1. examples/
  2. lib/
  3. products/
  4. runtimes/
  5. security/
  6. services/
  7. tools/