Remove defaults from configuration options as talked about in #23.

build.gradle

@@ -113,31 +113,26 @@ jupyter {
 
     kernelParameters {
         list('classpath', 'IJAVA_CLASSPATH') {
-            defaultValue = ''
             separator = PATH_SEPARATOR
             description = '''A file path separator delimited list of classpath entries that should be available to the user code. **Important:** no matter what OS, this should use forward slash "/" as the file separator. Also each path may actually be a simple glob.'''
         }
 
         list('comp-opts', 'IJAVA_COMPILER_OPTS') {
-            defaultValue = ''
             separator = ' '
             description = '''A space delimited list of command line options that would be passed to the `javac` command when compiling a project. For example `-parameters` to enable retaining parameter names for reflection.'''
         }
 
         list('startup-scripts-path', 'IJAVA_STARTUP_SCRIPTS_PATH') {
-            defaultValue = ''
             separator = PATH_SEPARATOR
             description = '''A file path seperator delimited list of `.jshell` scripts to run on startup. This includes ijava-jshell-init.jshell and ijava-display-init.jshell. **Important:** no matter what OS, this should use forward slash "/" as the file separator. Also each path may actually be a simple glob.'''
         }
 
         string('startup-script', 'IJAVA_STARTUP_SCRIPT') {
-            defaultValue = ''
             description = '''A block of java code to run when the kernel starts up. This may be something like `import my.utils;` to setup some default imports or even `void sleep(long time) { try {Thread.sleep(time); } catch (InterruptedException e) { throw new RuntimeException(e); }}` to declare a default utility method to use in the notebook.'''
         }
 
         string('timeout', 'IJAVA_TIMEOUT') {
             aliases NO_TIMEOUT: '-1'
-            defaultValue = '-1'
             description = '''A duration specifying a timeout (in milliseconds by default) for a _single top level statement_. If less than `1` then there is no timeout. If desired a time may be specified with a `TimeUnit` may be given following the duration number (ex `"30 SECONDS"`).'''
         }
     }