Falcon : ReLU and DReLU

[rasswanth-s]

Description

Implementation ReLU and DReLU functionality of Falcon. resolves #149

Affected Dependencies

List any dependencies that are required for this change.

How has this been tested?

Added tests for the same.

Checklist

• [x] I have followed the Contribution Guidelines and Code of Conduct
• [x] I have commented my code following the OpenMined Styleguide
• [x] I have labeled this PR with the relevant Type labels
• [x] My changes are covered by tests