Fix/add data and content type zendesk

[JoaoMacedo03]

Resolves #39

Description:
In the makeRequest method, the contentType is hardcoded to 'application/x-www-form-urlencoded'. Additionally, the 'data' parameter isn't being set, even when provided as an argument.

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Why is this change required?:
To have the flexibility to specify various contentTypes and utilize HTTP methods beyond just GET with ZAF.request.

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Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.