Make method names & events consistent between client and server

[inator]

See hoodiehq/camp#100 (comment)

[inator]

@gr2m & @mbad0la - thoughts on this? I suggest we could make these changes:

task.on('start', function(object, options) {})  // was 'add'
task.on('update', function(object, options) {})  // stays the same
task.on('stop', function(object, options) {}) // was 'remove'
task.on('change', function(eventName, object, options) {}) // stays the same

Note, we conceptualized a .restart() task-client method, so at some point we'll have to consider somehow firing a restart event as well, but that's for another issue.

[gr2m]

instead of update I suggest progress.
instead of stop I suggest success.
Let’s add error to the list.

The change event is good! There might be changes that neither start, nor progress, success or error. For that case we have different options

1. don’t emit a change event at all
2. set eventName to null
3. set eventName to update

I would suggest we postpone the change event for now, just like we do with restart. We don’t need it for a first iteration