Updated the UNIX bash script to check if Java is available on the path,
and if it is then also whether the version number is sufficient.
Currently only tested on Linux.
Made some changes to the brjs script that should hopefully make it Mac
compatible.
adding java install and version checking to windows script
Merge pull request #895 from BladeRunnerJS/java-install-help

Updated the UNIX bash script to check if Java is available on the path,