Include workflow execution creation as part of flytectl create workfl…

…ow (flyteorg#295)

* Stub for workflow

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Edit.

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Add WF execution steps

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Modified workflow steps.

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Fixing the rendering issue.

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Modified workflow as discussed.

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>

* Removed relaunch steps for workflow.

Signed-off-by: Alekhya Sai Punnamaraju <alekhyasaip@gmail.com>