Added getMiaHeaders to request interface

[FabioNappi]

Added function to request interface

Checklist

• your branch will not cause merge conflict with master
• run npm test
• tests are included
• the documentation is updated or integrated accordingly with your changes
• the code will follow the lint rules and style of the project
• you are not committing extraneous files or sensible data

[coveralls]

Coverage: 95.063%. Remained the same when pulling 11c583e on fix/request-interface into b1baabb on master.