Second (smaller) set of native core functions

This rounds out the first pass at a set of core functions, adding
some that were not in the first PR.

From here I'm working on a contrib.seq and contrib.io module to
hold less obvious but maybe interesting native functions that can
move to core if desired.

This should also close out issure #150 asking for some core
functions like these.
slightly cleaner version of drop-while, could use yield-from when ready
One more commit to change the test for Python 2/3 to a macro

Note that this can't use the macro in hy.core.macros so there
is a local copy in language.hy
finally fixed access to hy.core.macros here. have to explicitly require them
Various setup.py enhancements.

- PEP8 fixes
- Use setuptools.find_packages()
- Update PyPI classifiers
- Update website URL
- Install the argparse module in Python 2.6 and before
- Delete the duplicate rply in install_requires. With the PyPI
  version, tests are failed.
Merge branch 'patch-1' of https://github.com/berkerpeksag/hy into berkerpeksag-patch-1
Coerce the contents of unquote-splice'd things to a list

This fixes the conversion issue in the following macro:

(defmacro doodle [&rest body]
  `(do ~@body))
Add test for unquote-splice behavior
Always import __future__.print_statement in hy code

This allows us to drop the print special-casing in the
compiler, and makes behavior consistent in Python2/3.
Merge pull request #297 from olasd/print-function

Always import __future__.print_statement in hy code
Merge pullrequest #296
Add hy._compat module.

There was a couple of duplicate imports and type checkings in the
codebase. So I added a new module to unify all Python 2 and 3
compatibility codes.

Also, this is a somewhat common pattern in Python. See Jinja2 for
example:

https://github.com/mitsuhiko/jinja2/blob/master/jinja2/_compat.py
PY3 should really check for Python >= 3
Add @berkerpeksag to AUTHORS
Remove the redundant pass statement.
Update hacking guide.
Merge pull request #304 from berkerpeksag/patch-1

Update hacking guide.