gzip module is unused. ha!
updated test to only allow streaming of gzipped data, refactored read_file()
read_file() now always chunks by lines, don't need this
fix boto classname in comment
implement read in mockboto's MockKey
added test of gzipped data catted from S3
moved compression in tests into utility module
added bz2 test for s3 fs too
don't make everyone pay a performance penalty just because boto.s3.Key
doesn't behave like a proper file object