adding REST API documentation for uploading and downloading app
Update app bits api spec to better describe multipart application uploading.

[#65917050] Fixes #166

Signed-off-by: Phan Le <ple@pivotallabs.com>
Api specs should not reach under the hood

[#65917050]

Signed-off-by: Karl Isenberg <kisenberg@pivotallabs.com>
Merge branch 'brahmaroutu-rest_api_documentation'

[Finishes #65917050]