Rename travis_test.sh to test_travis.sh

It was breaking ./bin/t<TAB> -> ./bin/test and it was driving me nuts.
Make test_travis.sh not executable
Revert "Make test_travis.sh not executable"

This reverts commit 85886937514ae3d3f5105f45542d6d717ae03ee8.

Travis doesn't work if it isn't executable.
Merge pull request #1774 from asmeurer/travis_test

Rename travis_test.sh to test_travis.sh