Update travis build for docs sync

.travis.yml

@@ -1,7 +1,14 @@
 language: java
-install: mvn install -q -U -DskipTests=true -Dmaven.test.redirectTestOutputToFile=true
+before_install: git config user.name "$GIT_NAME" && git config user.email "$GIT_EMAIL"
+  && git config credential.helper "store --file=.git/credentials" && echo "https://$GH_TOKEN:@github.com" > .git/credentials
+install:
+  - mvn install -q -U -DskipTests=true -Dmaven.test.redirectTestOutputToFile=true
+  - ./src/main/asciidoc/ghpages.sh
 script: mvn --settings .settings.xml deploy -nsu -Dmaven.test.redirectTestOutputToFile=true
 env:
   global:
-  - secure: VsSFz5DO1BcI6Q9Hr/216DYLfo4FzZqD7LFZDa1VJqZUAtgy6/c0Z5E0vaIJOefpap/MoAHlNDloIwwtDIqCy4NLIUzzqZwmMeT+1hPdbLylQ61qr6UY34kMBmL00wH83iKZ65Z5FR5yhSjT0sNwfIDwEmt9etEsx64/vPNkcCI=
-  - secure: MThA8XhwSMcL8zv62olufrvYRTecnujimz0qZccjyMrpyZ5A6mWtHnpAIY4nYEoYNu+kAWPceaqO6bKn6wVv1xzP7ddJRxV5MmPkqt2S/WbqS1hp6gkOfclPdqRzz1NjEuAG8qu6m9EEn0NLsHhSfXl3mVz4huD0UUW+2AjUeN8=
+    - GIT_NAME="Dave Syer"
+    - GIT_EMAIL=dsyer@pivotal.io
+    - secure: VsSFz5DO1BcI6Q9Hr/216DYLfo4FzZqD7LFZDa1VJqZUAtgy6/c0Z5E0vaIJOefpap/MoAHlNDloIwwtDIqCy4NLIUzzqZwmMeT+1hPdbLylQ61qr6UY34kMBmL00wH83iKZ65Z5FR5yhSjT0sNwfIDwEmt9etEsx64/vPNkcCI=
+    - secure: MThA8XhwSMcL8zv62olufrvYRTecnujimz0qZccjyMrpyZ5A6mWtHnpAIY4nYEoYNu+kAWPceaqO6bKn6wVv1xzP7ddJRxV5MmPkqt2S/WbqS1hp6gkOfclPdqRzz1NjEuAG8qu6m9EEn0NLsHhSfXl3mVz4huD0UUW+2AjUeN8=
+    - secure: uM3piUpKZ018xCqVTlra1Io+nmV/Q79o3i6QzApqlQaIZBMxJI5M31wU3pHTkWGYfbi7H4+ehiRwi9knMxcPHb7o6nMyr+6tju3h3zUyScCh4prnC6v5JeyJmkA9aMG3s632l0T5vrwIoEonI6XxE0xd0ZuljQl1/vNXs9QUD5Y=

src/main/asciidoc/ghpages.sh

@@ -0,0 +1,46 @@
+#!/bin/bash -x
+
+git remote set-url --push origin `git config remote.origin.url | sed -e 's/^git:/https:/'`
+
+if ! (git remote set-branches --add origin gh-pages && git fetch -q); then
+    echo "No gh-pages, so not syncing"
+    exit 0
+fi
+
+if ! [ -d target/generated-docs ]; then
+    echo "No gh-pages sources in target/generated-docs, so not syncing"
+    exit 0
+fi
+
+# Stash any outstanding changes
+###################################################################
+git diff-index --quiet HEAD
+dirty=$?
+if [ "$dirty" != "0" ]; then git stash; fi
+
+# Switch to gh-pages branch to sync it with master
+###################################################################
+git checkout gh-pages
+
+for f in target/generated-docs/*; do
+    file=${f#target/generated-docs/*}
+    if ! git ls-files -i -o --exclude-standard --directory | grep -q ^$file$; then
+        # Not ignored...
+        cp -rf $f .
+        git add -A $file
+    fi
+done
+
+git commit -a -m "Sync docs from master to gh-pages"
+
+# Uncomment the following push if you want to auto push to
+# the gh-pages branch whenever you commit to master locally.
+# This is a little extreme. Use with care!
+###################################################################
+git push origin gh-pages
+
+# Finally, switch back to the master branch and exit block
+git checkout master
+if [ "$dirty" != "0" ]; then git stash pop; fi
+
+exit 0