Additional logging for launcher

[spchamp]

This patch would update the following plugin behaviors.

For processes initialized via BundleGemRunShortcut or LaunchConfigurationDelegate, a logging message will be created only on the following events:

• exception during process launch
• cancellation during process launch
• non-zero process exit

Details from the changelog:

ConfigHelper

• new class
• defining two static delegate methods for accessing a string config property, with logging for exceptions during config access

LaunchHelper

• new class
• defining a createJob method. This method provides a central implementation for calls that were implemented in both BundleGemRunShortcut and LaunchConfigurationDelegate, both creating a runnable Job spec for the DebugPlugin.
• the createJob method will log instead of throwing CoreException, if the process launcher is cancelled during createJob or if the external process exits with a non-zero exit status.

ReadaptDebugDelegate

• moving two constants to the class scope
• using ConfigHelper
• using LogHelper to log any exception when launching readapt
• updating the launch method signature, logging instead of throwing CoreException

BundleGemRunShortcut

• using LaunchHelper

RubyRunDelegate

• using ConfigHelper, LaunchHelper

LogHelper

• creating a constant for the bundle symbolic name
• creating two generic 'log' methods, here used within the 'info', 'error', and additional 'cancelled' methods
• adding an 'error' method accepting only a string arg
• adding a 'cancelled' method accepting only a string arg

This also removes the quote marks for argv0 in the readapt launcher

[spchamp]

The patch branch was started at the wrong change branch. That's all changes from my local contrib branch at this time.