Need to rename transaction to batch in http and gRPC endpoints.

[YourTechBud]

The transaction support we have added works more like a batch. Let's make that more explicit. This will require us refactoring:

• The https endpoint (url)
• The gRPC rpc name.
• The CRUD interface in crud.go and operations.go
• the func name in sql and mongo packages

[HeyItsJs]

Here's how the batch API should look for javascript:

const batch = db.beginBatch();
batch.add(db.insert(col).docs(...docs));
batch.add(db.update(col).where(whereClause).set())

// Apply batch
batch.apply().then(res => ...).catch(ex => ...)

Same can be ported to other client libraries as well

[KhushalPShah]

Have done the refactoring and have created a Pull Request.