[integration] Add support of Graal's CoCom Backend to ELK

[inishchith]

This thread addresses adding support of Graal's CoCom Backend and metrics visualization to ELK and Mordred.

• Implementation & Execution Reference:
  1. [integration] Add support of Graal to ELK & Mordred #4 (comment)
  2. [integration] Add support of Graal to ELK & Mordred #4 (comment)

• Work Branch - inishchith/grimoirelab-elk#gsoc-graal-2019-cocom
• Metrics reference issue: New Metrics: Support of source code related metrics chaoss/metrics#139
• Mordred would require alteration in configuration file along with documentation changes in future

[inishchith]

closing in reference to PR