Add failing test case for sax throwing
Wrap sax write and end methods in try/catch. Resolves #112
sax >= v0.6.0 can throw if a gzipped data stream containing certain characters gets written to the parser.
This is a user error (to pipe gzipped data), but sometimes servers send gzipped data even when you've told them not to. So, we try to let the user handle this more gracefully.