Re-add travis configuration and badge

Travis configuration was previously removed(@cf1dc613177) due to false negatives
caused by non-eterminism in the test environment. This issue can now be worked
around by defining DISABLE_NONDETERMINISTIC_TESTS before building.

So, this commit so this adds .travis.yml for automatic builds/tests on the
supported platforms and defines DISABLE_NONDETERMINISTIC_TESTS to skip tests
that can randomly fail. Each script under the .ci directory will be responsible
for building/testing a single platform or configuration.
Add CI configuration to build/test targeting x86