Eliminate Travis

[baentsch]

The reported Travis state is extremely misleading: It is shown as passing, while in reality, no test has apparently been running at all for "about a year":

This may be due to a change in Travis policy for the liboqs project (the banner is only visible when logging in):

This issue therefore suggests to completely remove Travis from CI reporting until this is fixed.

Travis is used exclusively for testing of IBM platforms (PPC and S390), so tagging @bhess and @planetf1 for comments. Also tagging @dstebila as #1605 documenting platform support status still is open...

[bhess]

Thanks @baentsch for opening the issue. I've sent an inquiry to TravisCI, hope it can be fixed.

[bhess]

The travis build is now re-enabled, see current error state:

I've created PR #1629 with a small update that makes the builds pass again.