Replace golang-migrate org with a new one in the tests

[carlosms]

For the initial work done in #131 we chose to use a small and stable organization, golang-migrate, for the tests.
We should replace it, creating a new organization owned by us, with the minimum amount of resources needed to test sourced-ce and ghsync.

[se7entyse7en]

Creating an organization, even if for open source, asks for these details:

How should we fill the billing email and the organization? For the organization, I guess sourced{d}.

[smacker]

@se7entyse7en let's create an issue for infra then.

[se7entyse7en]

Here it is link.

[se7entyse7en]

Moving this back to the backlog as it's blocked.