Navigation Bar and Table View for Roster

Preliminary table view for first tab, but there is a run-time error. Cannot figure out the problem.
Generally it's nice to name your sections using constants and reference those constants in the code:

```
static const NSUInteger kNumberOfSections = 2;
static const NSUInteger kStartersSection = 0;
static const NSUInteger kBenchSection = 1;
```

Generally having numbers like this in your code makes things harder to reason about. What does the number mean? Generally asking yourself that question and then naming a variable around that meaning will help your code be more readable.