Mention that Oracle JDK 6 library will fail to build

So people won't encounter and ask the same question as I did just now ;)

Author: Raymond Liu <raymond.liu@intel.com>

Closes #49 from colorant/doc and squashes the following commits:

90bf2aa [Raymond Liu] Mention that Oracle JDK 6 library will fail to build
Minor changes in Java POJO WordCount example
add gh_link jekyll plugin to docs