join sentences with a withspace

Join the replacetext with a whitespace. Otherwise two different sentence can be mixed. For eg:

url = http://timesofindia.indiatimes.com/tech/tech-news/Facebooks-Mark-Zuckerberg-in-India-today/articleshow/44740431.cms

a = g.extract(url)
a.cleaned_text

u'NEW DELHI: Facebook co-founder Mark Zuckerberg willon Thursday attend the two-day long Internet.org summit that aims to make internet access affordable for people who do not have it globally.Zuckerberg......'

Notice that there is no space between two sentences. This creates problem when later on, we want to split the cleaned_text using some sentence tokenizer.