Major updates:
* Support for reading text from STDIN: `$ cat path/to/collection/of/text/files/*.txt | sumgram -`
* Sumgram uses an [English stopwords](https://github.com/oduwsdl/sumgram/blob/c584e7eba1fab7deac1489aefa3f48f1b0d3ab64/sumgram/util.py#L33) list by default (switch off with `--no-default-stopwords`). To include additional stopwords `--add-stopwords`
* may be used to include additional stopwords:
$ sumgram --add-stopwords stopword1 stopword2 -t 10 path/to/collection/of/text/files/
* may be used to include additional stopwords in a text file (1 stopword per line):
$ sumgram --add-stopwords my_stopwords_file.txt -t 10 path/to/collection/of/text/files/
* Extracting/processing text from URLs:
$ sumgram "http://example.com/news/article-1.html" "http://example.com/news/article-1.html".
To change the default new article boilerplate removal method (`boilerpy3.ArticleExtractor`), set `--boilerplate-rm-method` with one of the following `'boilerpy3.DefaultExtractor', 'boilerpy3.ArticleSentencesExtractor', 'boilerpy3.LargestContentExtractor', 'boilerpy3.CanolaExtractor', 'boilerpy3.KeepEverythingExtractor', 'boilerpy3.NumWordsRulesExtractor', and 'nltk'` (regular expression for stripping all HTML tags)