addComment: Adds a comment to a thread on Labstep
In Labstep/labstepR: An R Package for Working with the Labstep API

This function allows you to comment on different content types

`user`	A labstep user object. Must contain an 'api_key' field. Returned from 'login' commande
`object`	The labstep object you want to comment on. Can be 'protocol', 'experiment' or 'resource'
`body`	The body of the comment in plain text.

Returns a 'comment' object

user <- login("demo@labstep.com","demopassword")
expName = 'My First Experiment'
expDesc = 'An experiment testing the labstepR library'
experiment <- createExperiment(user,expName,expDesc)
commentBody = 'An experiment testing the labstepR library'
comment <- addComment(user,experiment,commentBody)
print(comment)