Add Node.js to list of prerequisites for installation

docs/src/docs/development/installation/readme.md

@@ -24,6 +24,7 @@ This project has the following prerequisites:
 - **Languages**:
 	-   [**Scala**](http://www.scala-lang.org/) version 2.10.3
 	-   [**Java**](http://www.java.com/) (JDK version 1.7+)
+- **Runtime Environment**: [Node.js](http://nodejs.org/) 
 - **Cluster Computing**: To facilitate large tiling jobs, Aperture Tiles supports a cluster computing framework. Note that if you only intend to run small jobs (data sets that fit in the memory of a single machine) or are willing to take a long time to complete them, you can skip the Hadoop/HDFS/HBase installation and run Spark on a single node and read/write to your local file system.
 	-   **Apache Spark** - [Apache Spark](http://spark.incubator.apache.org/) distributed computing framework for distributing tile generation across a cluster of machines.  Aperture Tiles requires version 1.0.0 or greater. When you set up Spark, you also need to configure the version of Hadoop with which it will be working (if applicable). <p class="list-paragraph">NOTE: In the latest version of Spark, class path issues may arise if you compile Spark from the source code. For this reason, we recommend using one of the pre-built Spark packages.</p>
 	-   **Hadoop/HDFS/HBase** (Optional) - Distributed computing stack.  HDFS is a file system for storing large data sets. Choose your preferred flavor  ([Cloudera](http://www.cloudera.com/content/cloudera/en/products/cdh.html) version 4.6 recommended, though other flavors such as [Apache](http://hadoop.apache.org/docs/r1.2.1/index.html), [MapR](http://www.mapr.com/products/apache-hadoop) and [HortonWorks](http://hortonworks.com/) may work). HBase is a non-relational database that sits atop Hadoop/HDFS.<p class="list-paragraph">NOTE: Some cluster computing software may automatically install Apache Spark. If the automatically installed version is older than 1.0.0, you must upgrade to 1.0.0 or greater.</p>