Made multiple page requests optional + specs

Few changes I've did in this pull request: 
1. Added specs to the multiple page requests.
2. Added a flag to turn off multiple page request and made it *off* by default. 

Whenever making multiple page request, there is a sleep of 2 seconds between each page. Meaning that if by chance you make a query that has more than one page, your request will take >4 seconds which is quite high. Also, anyone who is updating to the latest version of the gem will start experiencing weird delays without understanding why... 

I think there is no debate that this flag is needed, but making it off by default is controversial. If you feel that you prefer it to be on by default, let me know and I will update my pull request.