Update HTTPHandler to send events with new-line seperation

[x]

My team and I ran into an issue with subscribing to the HTTPHandler from a web client. It seems like the existing format for the event doesn't match the W3 recommendation.

W3 specifies that there should be a an empty new-line character between events.

For example:

id: 0
event: add
data: this is the first event

id: 1
event: add
data: this is the second event

id: 2
event: add
data: this is the third event

Currently the HTTPHandler doesn't new-line separate.

For example:

id: 0
event: add
data: this is the first event
id: 1
event: add
data: this is the second event
id: 2
event: add
data: this is the third event

The existing client in this library doesn't care about this distinction, but a web browser such as Chrome or Safari or a JS client can't parse the events. Adding a new-line fixes this.

Making this change doesn't effect the current client because it defaults to no behavior.

[purehyperbole]

Excellent. Thanks for the PR!