added lib/linked_in/group to be required in lib/linkedin.rb
added lib/linked_in/group to be required in lib/linkedin.rb

NeverAgain/linkedin-oauth2,john/linkedin,sagmor/linkedin,Jobsrepublic-zzp/linkedin,hexgnu/linkedin,brianpetro/linkedin,backupify/linkedin,varunlalan/linkedin,emorikawa/linkedin-oauth2,EvilFaeton/linkedin