Add link to IDEA workspace instructions.

Change-Id: I85c2b537926f887bce0e0b370b6be6b56c038053

README.md

@@ -104,10 +104,15 @@ Note that the included Vaadin TestBench (browser) tests require access to a Test
 
 Building a package
 =====
-The distribution files can be built in two steps. 
+The distribution files can be built in two steps.
 
 1. Unpack required gwt jars into the project
 <pre><code>ant -f gwt-files.xml unpack.gwt</code></pre>
 2. Build the project by running
 <pre><code>ant</code></pre>
 in the project root directory (add -Dvaadin.version=1.2.3 to use a specific version number).
+
+Setting up other IDEs to Develop Vaadin 7
+=========
+- Unofficial instructions
+  - IntelliJ IDEA: http://github.com/Saulis/vaadin-idea-workspace/