getBanner
Loads an ASCII art banner from a classpath resource file, trims leading/trailing blank lines, and indents each line for display.
Banner text can be generated at: http://patorjk.com/software/taag/
Return
the formatted banner string with surrounding newlines
Parameters
filename
the classpath resource file containing the banner text
logger
a KLogger whose classloader is used to locate the resource
Throws
if the banner resource file is not found