[TUBEMQ-12]Change to use Apache License V2

[gosonzhang]

No description provided.

[yiheng]

can you highlight where do we enable RAT check? This change touches a lot of files. It's better to leave a comment on the change where enables the RAT check. (I try to search but not found)

[gosonzhang]

This PR only changed LICENSE of files, the " enable RAT check" is copied from Jira name.

This PR only changed the permissions of the files. After the completion, I found that nearly 400 files were modified. In order to avoid mutual influence, I will propose PR amendments one by one according to the topic.

[yiheng]

IMHO, the change is not reviewable without check in the enable RAT check change. No one can review such changes. Instead, if we enable the RAT check. The change can be verified automatically by the travis build job. Then we just need to review the RAT enable check change.

[guangxuCheng]

Agree with what @yiheng said.

[gosonzhang]

I checked the pom.xml, the rat check already existed, but not enabled in the CI script, but after the function was enabled, the entire compilation time took more than 20 minutes and it is not over yet.

It is better to enable RAT check locally before submitting pr or before incorporating the code, NOT in CI script.

[gosonzhang]

After enable the RAT check, I found that the PR compilation time has been extended a lot, so I reverted the modification of the travis-ci script.

Everyone can enable CAT check by adding "apache-rat: check" to the mvn command line