feat: #5. Add first commit date to initial repository data

[litvinovajann]

Closes #5

Resulting data before:

repo	repo_topics	creation	archive_url_creation	topic_present_creation	release	archive_url_release	topic_present_release
tiangolo/fastapi	"python,json,swagger-ui,redoc,starlette,openapi,api,openapi3,framework,async,asyncio,uvicorn,python3,python-types,pydantic,json-schema,fastapi,swagger,rest,web"	1544257307000	http://web.archive.org/web/20190204230405/https://github.com/tiangolo/fastapi	true	1544896765000	http://web.archive.org/web/20190204230405/https://github.com/tiangolo/fastapi	true

Resulting data after:

repo	repo_topics	first_commit_date	creation	archive_url_creation	topic_present_creation	release	archive_url_release	topic_present_release
tiangolo/fastapi	"python,json,swagger-ui,redoc,starlette,openapi,api,openapi3,framework,async,asyncio,uvicorn,python3,python-types,pydantic,json-schema,fastapi,swagger,rest,web"	1543993010000	1544257307000	http://web.archive.org/web/20190204230405/https://github.com/tiangolo/fastapi	true	1544896765000	http://web.archive.org/web/20190204230405/https://github.com/tiangolo/fastapi	true

[Relequestual]

Thanks for your contribution.
I am closing this in favour of #10.