add new formula to install Spring XD component

Spring XD makes it easy to solve common big data problems such as data ingestion and export,
real-time analytics, and batch workflow orchestration.
By building on mature, open source projects such as Spring Integration, Data and Batch,
Spring XD will simplify the process of creating real-word big data solutions.

spring-xd formula installs Spring XD component locally along with redis dependency as needed.