add cleanup task to Rakefile for generated files
place tests in Rakefile in 'test' namespace
split packets on any line ending using built-in method

Certain conditions around sending packets with CRLF line endings may
cause a KeyError exception to be raised. This changes the split() method
to not be specific to '\n', rather use the python splitlines() builtin
method to ensure we do not neglect Windows systems.

Fixes #1023
Merge pull request #1026 from DataDog/miketheman/line_endings

split packets on any line ending using built-in method