Switch to Ruby2 keyword arguments

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>
Bring README up to date

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>
Refactor Dropsonde#increment_counter to use #add_to_counter

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>
Implement Dropsonde#send_http_start

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>
Move convert_uuid to Events::UUID.from_string

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>
Test HTTPStart event with optional params

Signed-off-by: John Tuley <jtuley@pivotal.io>
Add Dropsonde#send_http_stop

[#80482302]

Signed-off-by: John Tuley <jtuley@pivotal.io>