Fix permissions for Singularity compatibility

Singularity can pull and run Docker images. However, since the command does not run as root, there are permission issues when trying to run some of the containers. This issue will track these bugs:

```
[dcl9@c1-05-2 ~]$ singularity exec docker://dukegcb/fastqc:0.11.4 fastqc
Docker image path: index.docker.io/dukegcb/fastqc:0.11.4
Cache folder set to /gpfs/fs0/home/dcl9/.singularity/docker
Creating container runtime...
/.singularity.d/actions/exec: 9: exec: fastqc: Permission denied
```

- [ ] fastqc