Add a generic endpoint to add/update all sections

[frankhart2018]

Closes #56 Closes #57 Closes #58 Closes #59 Closes #60 Closes #61 Closes #62 Closes #63 Closes #64 Closes #65 Closes #66

Implementation

1. All the updated felt repetitive to me, so I made it to a single section and a single generic PUT endpoint of the format: /resume/:section_name.
2. The body will look like:

{
    "section": {
        <section-obj>
    }
}

Apologies about the branch name, I started work and then realized that a generic solution is possible.