Changed image src path to relative.

Changed the setting's page to have the SwarmCDN logo image point to a
relative src instead of a hard-coded one, due to the variability of
locations and naming conventions of where users my install the plugin.

git-svn-id: https://plugins.svn.wordpress.org/swarm-cdn/trunk@759260 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added gitignore.

git-svn-id: https://plugins.svn.wordpress.org/swarm-cdn/trunk@759261 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated Readme

Renamed readme.md to readme.txt and updated to match Wordpress Directory
Guidelines.

git-svn-id: https://plugins.svn.wordpress.org/swarm-cdn/trunk@759263 b8457f37-d9ea-0310-8a92-e5e31aec5664
Removed old README

git-svn-id: https://plugins.svn.wordpress.org/swarm-cdn/trunk@759266 b8457f37-d9ea-0310-8a92-e5e31aec5664