Remove Reply (Legacy)

[mellistibco]

I'm submitting a ... (check one with "x")

[] bug report => search github for a similar issue or PR before submitting
[x] feature request
[] support request
[] general question

Current behavior (how does the issue manifest):
The Reply (Legacy) activity was left in flogo-contrib for backward compatibility.

Expected behavior:
Remove the Reply (Legacy) activity.

Minimal steps to reproduce the problem (not required if feature enhancement):

What is the motivation / use case for changing the behavior?
The Reply (Legacy) activity causes confusion because of the new Reply activity.

Please tell us about your environment (Operating system, docker version, browser & web ui version, etc):

Flogo version (CLI & contrib/lib. If unknown, leave empty or state unknown): 0.5.2

Additional information you deem important (e.g. issue happens only occasionally):