Add definition file for Travis CI

Add the most basic build definition file for Travis CI. It only
defines the project language as Java. For the rest the defaults
are kept as Travis seems to work fine with them.
We add `.travis.yml` as a dotfile in order not to clutter the
top directory with too much non-project files.

diff --git a/.travis.yml b/.travis.yml
new file mode 100644 (file)
index 0000000..a98b760
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,2 @@
+language: java
+