The head of the repo might be at a different location than the branch

So rely on the repo_commit object rather than repo_obj.head, this way
we should be able to create p-r fine
Add a representation for Issues objects
Add a string representation of the PullRequest objects
Add the GlobalId table

This table allows us to have a global identifier for the issues and
requests within a project.
For example:
  issue 1: global id: 1
  issue 2: global id: 2
  request 1: global id: 3
  issue 3: global id: 4
  request 2: global id: 5
Create the global id entry when creating an issue
Create the global id entry when creating a request
Retrieve the global identifiers when retrieving the list of issues of a project
Retrieve the global identifiers when retrieving the list of requests of a project
Retrieve a specific issue of a project using its global identifier
Retrieve a specific request of a project using its global identifier
Update the issues template to account for the global identifier change
Update the requests template to account for the global identifier change
Fix displaying the Merge button/Merged status in the pull_request template
Fix retrieving a specific issue via the global identifier
Fix retrieving a specific request via the global identifier
Order the results when retrieving the issues, requests list or specific entry
To view the diff of merged review we stop iterating when we reach the start commit
Forward the requestid when viewing a pull request
Use the requestid when creating the Merge link as we now use the global identifier
Get the list of issues of the correct project, not anyone