Switch to signed integers for all identifiers

[jasonmp85]

PostgreSQL doesn't have unsigned types, so using them when storing a value in a table doesn't make sense.

[jasonmp85]

Assigning to @sumedhpathak, since we discussed this a bit in #110…

[jasonmp85]

Reassigning to @onderkalaci because @sumedhpathak oversubscription, etc.

@onderkalaci can you look at this? It's pretty simple.

[onderkalaci]

@jasonmp85
I looked at the changes. All look fine.

• I ran regression tests
• Checked if this changes could lead to any problems (ie: signed-unsigned comparison problems). But, all changes look safe.
• I searched for other uint* usage. I see no other PostgreSQL related variable.

We can . I let you merge whenever you want to merge.