build: single quotes needed to upload any .cov file to codecov for reporting

Signed-off-by: Ron Evans <ron@hybridgroup.com>

.travis.yml

@@ -56,7 +56,7 @@ script:
    - echo "Checking that code is well-formatted"
    - make fmt_check
 after_success:
-   - bash <(curl -s https://codecov.io/bash) -f "*.cov"
+   - bash <(curl -s https://codecov.io/bash) -f '*.cov'
 branches:
    except:
       - gobot.io