Refactor CSV\Parser For Better Testing

We need refactor CSV\Parser::_readFileRow() to make it easier to test; then test it.

Right now the only way to truly test this method is to mock the file system.  I was trying to avoid this (mostly because I'm not real clear on how to set that up).  To avoid mocking the FS, we will need to move all FS operations into their own methods and modify the tests appropriately.
