Sync submodule to TF 1.2.0

Merge pull request tensorflow#325 from kirilg/0.5.1

Upstream changes to TF submodule

Merge pull request tensorflow#305 from kirilg/branch_146182478

Upstream internal changes

Merge pull request tensorflow#29 from chrisolston/update_submodules

Rolls forward to the latest versions of tensorflow and tf_models.

One more minor documentation fix.