CREATE: GET endpoint for Course-Information (CRN -> Section details)

[IgnasPanavas]

General Endpoint Requirements

1. Must use Spring Web annotations and syntax
2. Must have javadocs
3. Should be made in controller file of the specified micro service
4. Should return the return of an unimplemented function with an appropriate type, consider if the possible return parameter might be more than one
5. Comment out the name of the function for now and return an arbitrary value to not break the code at compile time, exception if the return type has a custom type that's not implemented yet, like Course for example. If it returns course it's ok for the code to not compile for now.
6. The function name should be logical given what you're retrieving

Specific Endpoint Requirements

1. Takes a CRN string as a required parameter
2. Also takes a header with the section fields that are requested to be returned, this makes the endpoint a lot more efficient and flexible. So when requesting, you can specify only class name or other fields that depend on use case.
3. Return a list of Sections that fit the criteria, assume Section.java is implemented
4. Don't forget to give the header information to the function as well

[IgnasPanavas]

I updated the expected format for all endpoints. Take a look at the changes in the Bulletin controller for what I'm looking them all to look like in the future. I'm adding time to this issue and all others to implement those changes. Thanks.