XD-472 Adding spring-xd-hadoop distro specific sub-projects

This will allow us to add a command line option for specifying
a --hadoopDistro option once we change start-up scripts to
support that.

Adding the following distros:

- hadoop10 - Apache Hadoop 1.0.4

- hadoop11 - Apache Hadoop 1.1.2

- hadoop20 - Apache Hadoop 2.0.5-alpha

- phd1 - Pivotal HD 1.0

We can add additional Cloudera cdh4 option if needed.