added docker image creation for experimental branch

.docker/experimental/Dockerfile

+FROM rocketchat/base:4
+
+ENV RC_VERSION experimental
+
+MAINTAINER buildmaster@rocket.chat
+
+VOLUME /app/uploads
+
+RUN set -x \
+ && curl -SLf "https://rocket.chat/releases/${RC_VERSION}/download" -o rocket.chat.tgz \
+ && curl -SLf "https://rocket.chat/releases/${RC_VERSION}/asc" -o rocket.chat.tgz.asc \
+ && gpg --verify rocket.chat.tgz.asc \
+ && tar -zxf rocket.chat.tgz -C /app \
+ && rm rocket.chat.tgz rocket.chat.tgz.asc \
+ && cd /app/bundle/programs/server \
+ && npm install \
+ && npm cache clear
+
+USER rocketchat
+
+WORKDIR /app/bundle
+
+# needs a mongoinstance - defaults to container linking with alias 'mongo'
+ENV MONGO_URL=mongodb://mongo:27017/rocketchat \
+    HOME=/tmp \
+    PORT=3000 \
+    ROOT_URL=http://localhost:3000 \
+    Accounts_AvatarStorePath=/app/uploads
+
+EXPOSE 3000
+
+CMD ["node", "main.js"]

.travis.yml

@@ -4,6 +4,7 @@ services:
 branches:
   only:
     - develop
+    - experimental
     - "/^(\\d+\\.)?(\\d+\\.)?(\\*|\\d+)$/"
 git:
   depth: 1

.travis/setartname.sh

@@ -2,5 +2,5 @@ if [[ $TRAVIS_TAG ]]
  then
   export ARTIFACT_NAME="$TRAVIS_TAG";
 else
-  export ARTIFACT_NAME="develop";
+  export ARTIFACT_NAME="$TRAVIS_BRANCH";
 fi