Release 4.5.0

[sijie]

Tracking the checklist for completing release 4.5.0

• Release Notes (feature highlights) Release Notes for 4.5.0 #356
• Configuration, Documentation for new features
  security: Documentation for security feature in 4.5.0 #349
  long poll: [documentation] lac piggyback and long pull read requests #359
  delay ensemble changes: [documentation] delay ensemble change #358
  settings: [documentation] configuration settings #360
• Upgrade story Documentation for upgrading 4.4 to 4.5 #355
• Performance Results (at least ensure no performance regression) Document performance difference between 4.4 and 4.5 #357

[sijie]

Release 4.5 is almost there. There are a few documentation items. We will defer to next release. Close this task now.