processors: html_processor and feature_extractor added

- html_processor takes document from field "body" in meta_info_t and
  sets field "text" with parsed html document

- feature_extractor takes document content from field "text" and builds
  terms frequencies array for words in that document. Then it sets this
  frequencies to field "terms_frequencies" in meta_info_t
Merge branch 'master' of github.com:reverbrain/wookie into HEAD
processors: Cosmetic fixes, Linking fixes

- html_processor links to libtidy and libmagic
- wookie::parser::text argument fixed
- extra newlines removed from processors files
Merge pull request #2 from IIoTeP9HuY/processors

html_processor and feature_extractor added