-d flag only finds *.yaml files and not *.yml

[bubbaksmith]

Kubeval skips any *.yml files when auto-detecting recursively through specified directories.

> tree
.
├── find_me.yml
└── test_deployment.yaml

0 directories, 2 files

> kubeval -d .
The file test_deployment.yaml contains a valid Deployment

>

[garethr]

Fixed in #177