Fix typo in Repository JSON key 'forks_count'
Fix typo in Repository JSON key 'forks_count'

It should be 'forks_count' instead of 'fork_count' according to https://developer.github.com/v3/repos/#get.
christophelec/github3.py,itsmemattchung/github3.py,h4ck3rm1k3/github3.py,krxsky/github3.py,wbrefvem/github3.py,ueg1990/github3.py,jim-minter/github3.py,sigmavirus24/github3.py,degustaf/github3.py,agamdua/github3.py,icio/github3.py,balloob/github3.py