Support hash fragment in uri matcher (e.g `#md5=...`)

[mshenfield]

The URI regular expression doesn't support hashes in the fragment portion. Because of this, these urls are ignored, and passed to pkg_resources parse, which fails in a confusing way.

import requirements
list(requirements.parse("http://pypi.python.org/packages/source/p/pytz/pytz-2012b.tar.gz#md5=6c47456aca37bec88b3c6f4b02db613a"))
# > RequirementParseError: Invalid requirement, parse error at "'://pypi.'"

Adding support for a hash fragment would be great!

[davidfischer]

These no longer fail after merging #23. However, I suppose it would be nice to try to get any additional information from the URL.

[davidfischer]

Thanks for fixing this in #24!