Add Travis CI config

Uses a PPA with back-ported libwebp to work around https://bugs.launchpad.net/ubuntu/+source/libwebp/+bug/1108731

.travis.yml

@@ -0,0 +1,16 @@
+language: node_js
+node_js:
+  - "0.10"
+before_install:
+  - sudo add-apt-repository ppa:lyrasis/precise-backports -y
+  - sudo apt-get update -qq
+  - sudo apt-get install -qq automake gobject-introspection gtk-doc-tools libfftw3-dev libglib2.0-dev libjpeg-turbo8-dev libpng12-dev libwebp-dev libtiff4-dev liborc-0.4-dev libxml2-dev swig graphicsmagick
+  - git clone https://github.com/jcupitt/libvips.git
+  - cd libvips
+  - git checkout 7.38
+  - ./bootstrap.sh
+  - ./configure --enable-debug=no --enable-cxx=no --without-python
+  - make
+  - sudo make install
+  - sudo ldconfig
+  - cd $TRAVIS_BUILD_DIR