Convert README to rst so pypandoc not needed

Github is happy with RST files, pypi is not. The easiest solution to
eliminating the need for pypandoc is to switch the file to RST.

This gets rid of the error when trying to `pip install configargparse`
without pypandoc being installed.
Merge pull request #4 from Pablosan/master

FIXES #2: Move configargparse.py to root of project
Merge branch 'Pablosan-pypandoc-fix'

Conflicts:
	setup.py
Some minor rewording to improve(?) clarity
minor rewording
include README.rst

This way README.rst will be included in the dist package
Refactored config file handling to fix issue #6. Reworded and expanded a few parts of the README
Fixed markup.
Added support for ~/ in config file paths. issue #7.
Added all classes from argparse module's namespace, and also defined a new HelpFormatter: ArgumentDefaultsRawHelpFormatter [issue #8]
Changed version to 0.9.3
Minor edits.
minor edits
minor edit
minor edit
added default config file paths to features list
minor edits
minor edits