Fix TypeError for pytest.skip()

pytests skip() method doesn't have a 'reason' parameter.
This fixes:

  TypeError: skip() got an unexpected keyword argument 'reason'

--HG--
branch : fix-type-error-skip-reason

--HG--
branch : fix-type-error-skip-reason

It fixes failure of setuptools.tests.test_sandbox.TestSandbox.test_setup_py_with_CRLF() with Python 3.1.

DistributionNotFound: Show requirers

--HG--
branch : DistributionNotFound_list_requirers

Disable warning of LegacyVersion in parsed_version. This functionality should be called explicitly at whatever times are appropriate for the warning. Fixes #307.

Update EGG_NAME regular expression matcher to allow names to include dashes. Fixes failing test and fixes #307.

It is very helpful to know who required the missing package. E.g.:

    pkg_resources.DistributionNotFound: The 'colorama>=0.3.1' distribution was not found and is required by smlib.log.

Note that there was a comment: "unfortunately, zc.buildout uses a str(err) to
get the name of the distribution here..", but I did a search in the `buildout`
code and I think that is no longer true, so I think that we're free to make the
exception message more helpful without risk of breaking buildout:

    # In clone from https://github.com/buildout/buildout
    $ ag DistributionNotFound
    src/zc/buildout/buildout.py
    686:        except (ImportError, pkg_resources.DistributionNotFound):

    $ pip install --download=. --no-install zc.buildout
    ...
      Saved ./zc.buildout-2.3.1.tar.gz
    ...
    $ tar xf zc.buildout-2.3.1.tar.gz
    $ ag DistributionNotFound zc.buildout-2.3.1
    zc.buildout-2.3.1/src/zc/buildout/buildout.py
    686:        except (ImportError, pkg_resources.DistributionNotFound):

--HG--
branch : DistributionNotFound_list_requirers