Fixed bug where syntax errors result in stack dump

I noticed that if there is a syntax error in the source file, that coffeelint throws an exception and dumps a stack trace rather than printing out the error in the appropriate format (csv, jslint, etc). This means any tools using coffeelint will see this as coffeelint crashing rather than the actual source file error.

My change just makes it so the lexical and line linting steps won't be performed if there is a syntax error in the source file.

Happy to make any adjustments if required, it was just a quick hack I did on my local install and thought you might appreciate.

Cheers