Update changelog for 0.5
v1beta3 Pod refactor
Add descriptions to all v1beta1 API fields.
Treat unset KUBERNETES_PROVIDER as gce.

Should fix jenkins failure.
Merge pull request #2434 from brendandburns/release

Update changelog for 0.5
Merge pull request #2444 from bgrant0607/docfix

Add descriptions to all v1beta1 API fields.
Merge pull request #2446 from erictune/secure_port_on

Treat unset KUBERNETES_PROVIDER as gce.
Document v1beta2 fields
Merge pull request #2097 from markturansky/v1beta3_podrefactor

Refactor internal API for Pods to match v1beta3
Fix tyop in authorization doc
Merge pull request #2454 from derekwaynecarr/fix_typo

Fix typo in authorization doc
Merge pull request #2452 from bgrant0607/docfix

Document v1beta2 fields