Fix tagcloud rendering behvaiour on special and wikipages

Additional content parsing is influenced by special page/template status.

An eyeball check on the following options (format=tagcloud):

1 link=all
2 link=none
3 template=TagCloud / link=none
4 template=TagCloud / link=all
5 widget=wordcloud / link=none
6 widget=wordcloud / link=all
7 widget=wordcloud / template=TagCloud
8 widget=sphere / link=none
9 widget=sphere / link=all
10 widget=sphere / template=TagCloud
bugfix (value filter does not filter out all empty values)

Added a case for empty values
Merge branch 'bugfix'
Merge pull request #16 from s7eph4n/master

bugfix (value filter does not filter out all empty values)
Update README.md
Create CONTRIBUTING.md
Update README.md
Update README.md
Update README.md
Update README.md
Update README.md
Update README.md
Merge branch 'master' of https://github.com/netbrain/SemanticResultFormats
removed dupes