Pytest

[matclab]

This PR ported the existing tests as an automated py.test file in test/test_fabricate.py, and add a travis configuration file to allow continuous integration on Travis.

The current status is not so good :

test/test_fabricate.py::test_create[StraceRunner] FAILED
test/test_fabricate.py::test_create[AtimesRunner] PASSED
test/test_fabricate.py::test_mkdir[StraceRunner] PASSED
test/test_fabricate.py::test_mkdir[AtimesRunner] FAILED
test/test_fabricate.py::test_rename[StraceRunner] xfail
test/test_fabricate.py::test_rename[AtimesRunner] xfail
test/test_fabricate.py::test_symlink[StraceRunner] PASSED
test/test_fabricate.py::test_symlink[AtimesRunner] FAILED
test/test_fabricate.py::test_md5_hasher PASSED

The StraceRunner failed tests may be linked to existing issues like #42.
The rename tests are written as "expected failed", because the dependency on the origine file is never recorded (issue to be opened).
I'm not sure about the AtimesRunne issues.