creation of the broadRsearch package

[rpietro]

idea is to emulate what is done by http://goo.gl/tPFwr , but creating a function that will search not only for http://finzi.psych.upenn.edu/search.html but also http://www.rseek.org , https://github.com/search and potentially even other custom search engines using http://www.google.com/cse/manage/all

the package should be formatted according to http://goo.gl/Oww76 and http://goo.gl/Af265