Update version to 0.12.13

0.12.12

increase version to 0.12.11 (tensorflow#1224)

Bump version to 0.12.10 (tensorflow#1216)

update the version to 0.12.9 (tensorflow#1206)

Update version to 0.12.8 (tensorflow#1189)

Update core to 0.12.7 (tensorflow#1187)

DEV

Bump version to 0.12.6 (tensorflow#1182)

update version to 0.12.5

Update to 0.12.4. (tensorflow#1164)