Update latest Selenium beta release to 3.0.0-beta4

Author: davehunt

Base/Dockerfile

@@ -28,7 +28,7 @@ RUN apt-get update -qqy \
 #==========
 RUN  mkdir -p /opt/selenium \
   && wget --no-verbose https://selenium-release.storage.googleapis.com/2.53/selenium-server-standalone-2.53.1.jar -O /opt/selenium/selenium-server-standalone-2.53.1.jar \
-  && wget --no-verbose https://selenium-release.storage.googleapis.com/3.0-beta3/selenium-server-standalone-3.0.0-beta3.jar -O /opt/selenium/selenium-server-standalone-3.0.0-beta3.jar
+  && wget --no-verbose https://selenium-release.storage.googleapis.com/3.0-beta4/selenium-server-standalone-3.0.0-beta4.jar -O /opt/selenium/selenium-server-standalone-3.0.0-beta4.jar
 ENV SELENIUM_VERSION=2.53.1
 
 #========================================

README.md

@@ -63,7 +63,7 @@ these using the following environment variables:
 
 - `SELENIUM_VERSION` - version of the Selenium server
   - latest stable: `2.53.1`
-  - latest beta: `3.0.0-beta3`
+  - latest beta: `3.0.0-beta4`
 - `FIREFOX_VERSION` - version of Firefox (only applies to Firefox images)
   - latest release: `49.0.1`
   - previous release: `48.0.2`
@@ -74,11 +74,11 @@ Note that as the latest releases of Firefox work best with Selenium 3.0, which
 is currently in beta, the latest release supported by 2.53.x is `47.0.1` and is
 also available (and the default).
 
-For example, the following will start a standalone server using Selenium 3.0.0-beta3
+For example, the following will start a standalone server using Selenium 3.0.0-beta4
 and Firefox 49.0.1:
 
 ```bash
-$ docker run -d -p 4444:4444 -e SELENIUM_VERSION=3.0.0-beta3 -e FIREFOX_VERSION=49.0.1 selenium/standalone-firefox:latest
+$ docker run -d -p 4444:4444 -e SELENIUM_VERSION=3.0.0-beta4 -e FIREFOX_VERSION=49.0.1 selenium/standalone-firefox:latest
 ```
 
 ### JAVA_OPTS Java Environment Options