Add UVI API

[peter279k]

Change log

• Add UVI API.
• Remove allow_failures configuration.

I'm not sure it's the proper way to implement the UVI API.
Please review this.

Thanks.

[cmfcmf]

Could you please revert these changes or reason why you made them?

[peter279k]

Hi @cmfcmf, I remove the nightly because I think the master branch should be passed by the nightly,
And it shouldn't allow failures.

Secondly, I move the if [[ ! $TRAVIS_PHP_VERSION = hhvm* ]]; then phpenv config-rm xdebug.ini || echo "xdebug not available"; fi to the install step.

Thanks.

[cmfcmf]

I think the master branch should be passed by the nightly,

I must disagree here, I've reverted this change in my PR #99.
Please take a look at #99. It includes most of your changes plus a few adjustments. Thank you for your work!