reorders left sidebar, edits to wordpress plugin page, minor edit to main landing page
adds link to additonal tracking settings for better explanation
adds screenshots of WP plugin installation in action
adds info about WP filters
adds additional info on advanced tracking settings and reorders some things
some minor formatting fixes
adds encrypted email links and updated screenshot containing an actual PID
small edits to section on entering PID
replaces all PIDs with a dummy PID that doesn't exist
Merge pull request #14 from simplereach/feat/liz/doc_updates/229

updates to WordPress plugin page