Installing docutils requires tgz extension

In order to get pip to recognize that docutils was a tar.gz, I needed to make the extension .tgz or .tar.gz, so update the instructions.
Merge pull request #34 from jasongrout/patch-1

Installing docutils requires tgz extension
Fix extension in README instructions
Small cleanup/bugfix in in_tag method for html converter.

Fix missing quotes and spaces in in_tag, avoid a += string loop.
Also, fix missing quotes in header.
Update markdown requirement.
Remove _files directory at the end if empty.
Remove unused md2html function.

We now know that the full html output is usable in blogger.
Add blogger-html format option.

This simply generates the output in two files, one with the header
(used to customize blogger setup) and a separate one with the html
body alone.
add raw-based sphinx notebook extension
cleanup implementation
ENH: split main_body() from convert() in Converter base class
sphinx: remove duplicate html, head, & body tags; use scoped attribute
add missing html classes to output div
fixed typo
added documentation to more functions and methods
make automatic __doc__ inheritance

our previous implementation was not actually working prior to this.

Now, for the converters which inherit from Converter, we don't
have to keep adding the @DocInherit decorators.

Also, removed a function that was no longer being used in the code.

Before this commit:
-------------------
In [1]: import nbconvert; nbconvert.ConverterBloggerHTML.render_code?
Type:       instancemethod
String Form:<unbound method ConverterBloggerHTML.render_code>
File:       /home/pi/code/nbconvert/nbconvert.py
Definition: nbconvert.ConverterBloggerHTML.render_code(self, cell)
Docstring:  <no docstring>
-------------------

After this commit:
------------------
In [1]: import nbconvert; nbconvert.ConverterBloggerHTML.render_code?
Type:       instancemethod
String Form:<unbound method ConverterBloggerHTML.render_code>
File:       /home/pi/code/nbconvert/nbconvert.py
Definition: nbconvert.ConverterBloggerHTML.render_code(self, cell)
Docstring:
Convert a code cell

Returns list.
-------------------
robust css/preamble path finding despite symlinks

I have a `~/bin/nbconvert` symlink to ~/code/nbconvert/nbconvert.py so
that I can call it from anywhere in the filesystem. Stylesheets were
found previously using `__file__`, which can change depending on where
one puts symlinks.

Additionally, I found one other place where such a situation was
anticipated, but the solution was using a bit too much code. The
simplest way to get around this situation is to used `os.path.realpath`,
which is what I've done here.

Here's a traceback of the error, in case someone stumbles into this.
$ nbconvert -f html test_display.ipynb
Traceback (most recent call last):
  File "/home/pi/bin/nbconvert", line 1490, in <module>
    main(infile=args.infile[0], format=args.format)
  File "/home/pi/bin/nbconvert", line 1459, in main
    htmlfname = converter.render()
  File "/home/pi/bin/nbconvert", line 311, in render
    self.output = self.convert()
  File "/home/pi/bin/nbconvert", line 293, in convert
    lines.extend(self.optional_header())
  File "/home/pi/bin/nbconvert", line 808, in optional_header
    return ['<html>', '<head>'] + self.header_body() + \
  File "/home/pi/bin/nbconvert", line 790, in header_body
    header.extend(self._stylesheet(sheet))
  File "/home/pi/bin/nbconvert", line 756, in _stylesheet
    with io.open(fname, encoding='utf-8') as f:
IOError: [Errno 2] No such file or directory: '/home/pi/bin/css/static_html.css'
Merge pull request #35 from jakevdp/sphinx-extension

WIP: Sphinx Notebook Extension
Merge pull request #39 from Carreau/htmloutput

add missing html classes to output div
Merge pull request #40 from ivanov/auto-docinherit

make automatic __doc__ inheritance