Adds Twitter username from settings to template
Replaces substr with ltrim
Updates changelog
Adds Twitter to backend settings
Fixes indentation
Don't rewrite existing functionality.

The difference between errors in debug mode and non-debug mode is
allready handled. We don't need to rewrite this ourselves in the tags
function.
Merge pull request #832 from forkcms/bugfix-tags-error-handling

Don't rewrite existing functionality.
Merge branch 'feature-twitter-name-forkcms' of github.com:jonasdekeukelaere/forkcms into jonasdekeukelaere-feature-twitter-name-forkcms

Conflicts:
	CHANGELOG.md
Merge branch 'jonasdekeukelaere-feature-twitter-name-forkcms'