Update travis build

We need to manually build of vips from master because of the Poppler
requirements that is too strong in 8.3.3.

.travis.yml

@@ -1,3 +1,6 @@
+sudo: required
+dist: trusty
+cache: apt
 language: go
 
 go:
@@ -5,8 +8,46 @@ go:
   - 1.5
   - tip
 
+addons:
+  apt:
+    packages:
+      - gobject-introspection
+      - gtk-doc-tools
+      - libcfitsio3-dev
+      - libfftw3-dev
+      - libgif-dev
+      - libgs-dev
+      - libgsf-1-dev
+      - libmatio-dev
+      - libopenslide-dev
+      - liborc-0.4-dev
+      - libpango1.0-dev
+      - libpoppler-glib-dev
+      - libwebp-dev
+
+# VIPS 8.3.3 requires Poppler 0.30 which is not released on Trusty.
 before_install:
-  - curl -s https://raw.githubusercontent.com/lovell/sharp/master/preinstall.sh | sudo bash -
+  - wget https://github.com/jcupitt/libvips/archive/master.zip
+  - unzip master
+  - cd libvips-master
+  - ./autogen.sh
+  - >
+    CXXFLAGS=-D_GLIBCXX_USE_CXX11_ABI=0
+    ./configure
+    --disable-debug
+    --disable-dependency-tracking
+    --disable-introspection
+    --disable-static
+    --enable-gtk-doc-html=no
+    --enable-gtk-doc=no
+    --enable-pyvips8=no
+    --without-orc
+    --without-python
+    $1
+  - make
+  - sudo make install
+  - sudo ldconfig
+  - cd ..
 
 before_script:
   - go get -u github.com/golang/lint/golint

image_test.go

@@ -23,21 +23,21 @@ func TestImageResize(t *testing.T) {
 func TestImageGifResize(t *testing.T) {
 	_, err := initImage("test.gif").Resize(300, 240)
 	if err == nil {
-		t.Errorf("GIF shouldn't be saved within VIPS.")
+		t.Errorf("GIF shouldn't be saved within VIPS")
 	}
 }
 
 func TestImagePdfResize(t *testing.T) {
 	_, err := initImage("test.pdf").Resize(300, 240)
 	if err == nil {
-		t.Errorf("PDF cannot be saved within VIPS.")
+		t.Errorf("PDF cannot be saved within VIPS")
 	}
 }
 
 func TestImageSvgResize(t *testing.T) {
 	_, err := initImage("test.svg").Resize(300, 240)
 	if err == nil {
-		t.Errorf("SVG cannot be saved within VIPS.")
+		t.Errorf("SVG cannot be saved within VIPS")
 	}
 }