Add deploy setup for gh-pages

.travis.yml

@@ -68,8 +68,15 @@ addons:
     - libcurl4-openssl-dev
     - libelf-dev
     - libdw-dev
-after_success:
-- travis-cargo --only stable doc-upload
+after_success: |
+  [ $TRAVIS_BRANCH = master ] &&
+  [ $TRAVIS_PULL_REQUEST = false ] &&
+  cd .imag-documentation &&
+  cargo doc &&
+  echo "<meta http-equiv=refresh content=0;url=`echo $TRAVIS_REPO_SLUG | cut -d '/' -f 2 | sed 's/-/_/'`/index.html>" > target/doc/index.html &&
+  sudo pip install ghp-import &&
+  ghp-import -n target/doc &&
+  git push -fq https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git gh-pages
 notifications:
   email:
     on_success: never