Remove tag creation and erb whitespace clear

That implements 'trim' mode in native ERB - whereas in Puppet (and also in Rails, apparently), you'd use the dash/minus - for example `-%>` to indicate that whitespace is suppressed/removed - in native ERB, this is achieved by specifying `'<>'` as the third argument ... more here => http://stackoverflow.com/a/15189263/1326879
and
http://craiccomputing.blogspot.co.uk/2010/04/suppressing-newlines-in-ruby-erb.html

I've also just discovered that you can also use `'-'` apparently, perhaps that would be a better approach, as it's something we're familiar with already - http://stackoverflow.com/a/13568485/1326879