Cosmos DB api testing

This is a fork from this original repo. Main changes include:

Updated to the latest API version of 2018-12-31.
Focused more on document operations than database and collection operations.

To install:

Import CosmosDBSQL.postman_collection.json to Postman collections.
Import CosmosDBSQLEnv.postman_environment.json to Postman environment.

To Use:

Replace DocumentDBHost and DocumentDBMasterKey in the environment with your Cosmos DB settings.
Replace mydb, mycol, mydocid, mydocpartitionkey in the url or headers of the request with your values. Note that these values in the url must be hardcoded. They can't be environment variables, as they are used in the script to compute the auth key. For example:
Replace request body with your document or query content.
In the response header, you will see x-ms-request-charge, which is the Cosmos DB RU (Request Unit) incurred by the request.