Small readability and consistency fixes for README
Add a sample Apache conf file and HACKING instructions

On XAMPP, the provided .htaccess file doesn't work out of the box,
and resists being used if the site is served from a subdirectory
(http://localhost/crosswalk-website for example).

I ended up using a separate configuration file on the directory
containing the project, and ignoring the .htaccess file, replacing
its rewrite rules with my own. This doesn't impact on the use
of .htaccess in the production version of the site, but makes
setup easier in environments where .htaccess isn't suitable.
Add a note about generated content preventing developer site working
Add note about live editing of content through gollum
Add more explanation of how live/staging work to README
Add some 'content management' notes
Merge pull request #30 from townxelliot/docs

Separate main documentation from hacking instructions