Add Russian word tokenizer test
Set output mode to UTF-8 in unit tests so no "Wide character ..." warnings are emitted
Add comment about why each word is re-lowercased
Fix comment wording
Run test similarity scoring 1000 times to get a better performance measure
Move the word tokenization / stemming / counting work into a subroutine to make it cacheable (memoizable)
Add explanation about why 'words_in_text_2' is foreached and not 'words_in_text_1'
Adjust the manual text similarity test so that it better reflects how the similarity scoring is used in real world
Memoize output of MediaWords::Util::Text::_words_in_text() helper because parameter #1 of get_similarity_score() is going to be "title+description" (constant for each text line passed as parameter #2)