Numeric permissions can Solve your problem.
sudo chmod 775 'your directory' 
Most of you guys like to know why always developer use chmod 775 to manage permission issue.
- 400 read by owner
- 040 read by group -
- 004 read by anybody
- 200 write by owner
- 020 write by group
- 002 write by anybody
100 execute by owner 010 execute by group
- 001 execute by anybody
400 +040 +004 +200 +020 +100 +010 +001 =775
This will give permission, but cannot write by anybody.