Add web ui for liberator request traces.
Include request headers in log.
Show request and request parameters in trace ui.
Rework logging
* Supports multiple loggers
* Newer dependencies
* Fix some examples.
Add dev trace panel to olympics example page

Example: add link to trace ui
Dev:
* Increase request log size to 100
* dev: Rename data-ago to seconds-ago
* Fix corrupt merge artifaces in core
Core:
* Use simple merge to combine default values for
  handler result with actual handler result
Fix namespace alias to dev in examples
Make loggers accept variable number of args
Fix generation of headers (etag, last-modified). Add test for it.
Extract wrap-trace,  provide wrap-trace-ui and wrap-trace-header.
Return the actual header value in header-exists?

* This makes the liberator trace more usefull as it contains the
  actual values whenever a header is checked for existence.
WIP Extract dot diagram from core.clj

* Redirection status are broken at the moment.
Fix handlers for redirection status 301, 303, 307
Adjust graph to show actions on same rank

* Output graph to a string instead of printing to *out*
Colorize handlers in flow graph according to http status class
Add trace for decisions separate from log.

This can be used to highlight the path taken in the decision graph.
Generate graphviz-safe ids for nodes
Add index to examples

* Also add a default greeting and text/html to the hello-george example
Adds svg flow chart to trace ui

* Move graph generation to main src
* Add generated graph and css as resource
* Highlights path in flow chart in trace view
* Adjust examples
Make run-handler return etag and last modified by default
Move data functions to liberator.util