Allow specification of an architecture when installing node. There are some npm modules that don't work on x64.

Usage example:

...
<execution>
    <id>install node and npm</id>
    <goals>
        <goal>install-node-and-npm</goal>
    </goals>
    <configuration>
        <nodeVersion>v0.10.28</nodeVersion>
        <npmVersion>1.4.9</npmVersion>
        <architecture>x86</architecture>
    </configuration>
</execution>
...