Updated Developer Guide (markdown)

Developer-Guide.md

@@ -43,12 +43,15 @@ as described below.
 The minimum requirements are:
 
 * Git
+* [Node.js](http://nodejs.org/) 
 * Python 2.6 or 2.7 with a couple of extra modules (see below)
 * Java 7 (JRE and JDK)
-* [Node.js](http://nodejs.org/) 
-* [PhantomJS](http://phantomjs.org/) 1.6 or higher
 
-The executables `git`, `java`, `jar`, `python`, and `phantomjs` should be in your `PATH`.
+The executables `git`, `java`, `jar`, and `python` should be in your `PATH`.
+
+To install the Node.js dependencies run
+
+    $ npm install
 
 To install the extra Python modules, run:
 
@@ -59,12 +62,6 @@ or
 
 depending on your OS and Python installation.
 
-To install the Node.js dependencies run
-
-    $ npm install
-
-Note: another way to set up your development environment is to use Hadrien Tulipe's [Docker image](https://github.com/htulipe/ol3-docker-env). This will create a virtual Ubuntu machine with all the dependencies installed for you.
-
 ## Working with the build tool
 
 As an ol3 developer you will need to use the `build.py` Python script. This is