Automate www. deployment through Alkane

Summary:
Once a new commit reaches Jenkins CD, this pipeline triggers
a new deployment through Alkane HTTP API.

The API end-point is web-001, currently in IP form, as the Docker
container running the agent uses an external DNS and, as such,
ignores /etc/hosts on the Docker engine.

The context is compatible with _lib/git-clone.sh Alkane recipe.

Test Plan: Request has been checked with curl -X POST

Reviewers: aceppaluni

Reviewed By: aceppaluni

Differential Revision: https://devcentral.nasqueron.org/D3439