Added Changes section and related text (closes #116)

Please note that tidy cleaned up some recent commits.
Merge pull request #117 from marcoscaceres/changlog

Added Changes section and related text (closes #116)
fixed merge conflicts
Merge pull request #123 from marcoscaceres/markup_fixes

Markup fixes, typos, and other minor things
Merge branch 'gh-pages' into noLegacyStyle
Removed duplicate changes section
moved telephonycall interface outside CallHandler
Butchered the EventHandler definitions…