Create a cron job to check this project with the latest OpenThread?

[bukepo]

Is your feature request related to a problem? Please describe.
It's possible to find this project is not compatible with the latest OpenThread too late. A daily cron job in Travis could help us to find the incompatibility in time.

Describe the solution you'd like
Create travis job to check with the latest OpenThread.

Additional context
#16

[jwhui]

Doing this would mean that Travis would report the master branch as broken, even when it is not really broken since submodule points to an older commit of openthread/openthread.

Thoughts?

[bukepo]

Yes. How about we create a new project which just contains Travis scripts to check compatibility among all OpenThread projects, such as OpenThread, Wpantund, ot-br-posix and ot-rtos?