Add a config for the travis-ci.org continuous integration system. r=tmatth

Based on the config from the opus project.

Author: rillian

.travis.yml

@@ -0,0 +1,13 @@
+language: c
+
+env:
+  - CONFIG=""
+  - CONFIG="--enable-fixed-point"
+  - CONFIG="--enable-fixed-point --disable-float-api"
+  - CONFIG="--enable-vorbis-psy"
+  - CONFIG="--disable-binaries"
+
+script:
+  - ./autogen.sh
+  - ./configure $CONFIG
+  - make distcheck