Update main class to reflect use of JarLauncher

b19f6bb238 updated the CLI so that it should be launched using Spring
Boot Loader's JarLauncher, however the spring and spring.bat shell
scripts were not updated so they still launched the CLI by using
SpringCli as the main class. This led to a NoClassDefFoundError
as none of the dependencies in the jar's /lib directory could be
found.

This commit updates the two shells scripts to use JarLauncher as the
main class.