#775 Set loglevel when debug arg is provided

Moved the logic that sets LogLevel to debug when Debug is provided from
ArgumentParser to ArgumentHandler.

Added tests for when Debug is provided on command line and in the opts
file.

Removed test from the ArgumentParserTests that is no longer valid.
Merge pull request #821 from ryanrousseau/775

#775 Set loglevel when debug arg is provided
Add support for global opts file - fixes #768

FileSystem.GlobalOptsFile will return the path for a scriptcs.opts file
in the ModulesFolder

ArgumentHandler looks for non-default option values first from the
command line, then from a local opts file if it exists, and finally from
a global opts file if it exists.

Rename ModulesFolder to GlobalFolder per discussion on #768

Update ShouldUseScriptOptsIfParsingFailed: parser mock will create a
ScriptCsArgs instead of returning null to avoid null reference exception