fix: Addressing an issue with quotations appearing in the docker environment variables (#182)

# Fix docker environment variable quotes

## Description
Addressing an issue with quotations appearing in the docker environment
variables.

## Type of Change
Please select the type of change your pull request introduces:
- [x] Bugfix
- [ ] New feature
- [ ] Documentation update
- [ ] Other (please describe):

## Checklist
- [x] This PR conforms to the process detailed in the [Contributing
Guide](https://sandialabs.github.io/firewheel/developer/contributing.html).
- [x] I have included no proprietary/sensitive information in my code. 
- [x] I have performed a self-review of my code.
- [x] I have commented my code, particularly in hard-to-understand
areas.
- [x] I have made corresponding changes to the documentation.
- [x] My changes generate no new warnings.
- [x] I have tested my code.

Author: sdelliot

docker/fsroot/start-minimega.sh

@@ -19,9 +19,16 @@ fi
 if [[ -f "/etc/default/minimega" ]]; then
     # Check if any variables are already set
     while IFS='=' read -r key value; do
-        # Only set the variable if it is not already set
-        if [[ -z "${!key}" ]]; then
-            export "$key"="$value"
+        # Skip empty lines and comments
+        if [[ -n "$key" && -n "$value" && "$key" != \#* ]]; then
+            # Remove surrounding quotes
+            value="${value%\"}"
+            value="${value#\"}"
+
+            # Only set the variable if it is not already set
+            if [[ -z "${!key}" ]]; then
+                export "${key}=${value}"
+            fi
         fi
     done < <(grep -v '^#' "/etc/default/minimega")
 fi