Setup Travis-CI.

- .travis.yml
- update README.txt about testing
- setup.py hard-depends on setuptools to get extras support.
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..3a5202b
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,12 @@
+language: python
+python:
+  - "2.6"
+  - "2.7"
+  - "3.2"
+  - "3.3"
+  - "3.4"
+  - "nightly"
+# command to install dependencies
+install: pip install .[test]
+# command to run tests
+script: unit2