feat: default safe search enabled for Google search

[AnsahMohammad]

trafficstars

by default set safe = "active" inorder to turnoff, one can add the parameter in kwargs as safe = "off"

usage:

search_args = ('hello world', 1)
gsearch = GoogleSearch()
gresults = gsearch.search(*search_args, safe='off') 

This PR will close #126