Added destructor to ConnectionGrammar which attempts to disconnect.
Added test cases for logging framework.
Clean up Sphinx config and use default theme

I removed some old commented out code, updated date formats to
YYYY-MM-DD, and updated the copyright year to 2014. I changed the
Sphinx theme to "default" so that Read the Docs will use its new
theme as explained here:
http://ericholscher.com/blog/2013/nov/4/new-theme-read-the-docs/
Use double quotes for string escaping
Add engine prefix to recobs and timer loggers

The recobs and timer objects are part of the engine infrastructure, and
their logger objects should therefore have the engine prefix.
Simplify logging infrastructure

Changes to dragonfly/log.py:
 - Remove logger prefix mechanisms, including get_log() function.
 - Remove debug outputting of various message processing.
 - Add removal of old dispatching handlers to setup_log().
 - Removed set_log_level().

Changes to dragonfly/test/test_log.py:
 - Comment out printing of output at test case teardown.
 - Remove test case for absence of no-handlers error message.
 - Add verification logic to filtering test case.
 - Remove test case for set_log_level().
 - Remove test case for file output.
Remove debug printing from parser test cases
Add more tests to test suites
Re-factor content and file structure of docs

I restructure the documentation to better match the source code structure,
i.e. it's now structured along the lines of engines, grammar, actions,
etc. I split the grammar documentation up into separate files for the
grammar, rules, and elements classes. I also added empty placeholders
for new topics, such as the release process.
Fix broken autodoc links to engine classes