Let Travis update the "snapshot" tag after every build

This required a GitHub deployment key with write access to
be added to the repository. It is encrypted with by using
the encrypt-file functionality of Travis. See here:

http://docs.travis-ci.com/user/encrypting-files/

Author: denisw

.travis.yml

@@ -6,3 +6,4 @@ jdk:
 
 after_success:
   - mvn -DserviceJobId=$TRAVIS_JOB_ID clean cobertura:cobertura coveralls:cobertura -Dcobertura.report.format=xml
+  - ./.travis/update_snapshot_tag.sh

.travis/deploy_key.enc

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+[email protected]:buddycloud/buddycloud-server-java.git
+
+# Decrypt the deployment key for Git push access
+openssl aes-256-cbc -K $encrypted_937d176d0339_key -iv $encrypted_937d176d0339_iv -in .travis/deploy_key.enc -out .travis/deploy_key -d
+ssh-add .travis/deploy_key.enc
+
+# Import the deployment key
+chmod 600 .travis/deploy_key
+eval `ssh-agent -s`
+ssh-add .travis/deploy_key
+
+# Set Git committer information
+git config user.name "Travis CI"
+git config user.email "[email protected]"
+
+# Remove the `snapshot` tag and re-add it to point to the latest commit
+git tag -d snapshot
+git push $GIT_URL :snapshot
+git tag -a snapshot -m "Latest Snapshot"
+git push --tags $GIT_URL