Add option to limit transitive dependency analysis

[gramster]

I can see at least two useful limits:

• skip third party imports
• skip transitive third party imports

[qubitron]

The ability to exclude specific packages may be helpful as well as a workaround if future problems arise

[MikhailArkhipov]

Since we now have depth setting it is doable, but per @AlexanderSher typically graph is much wider than deeper so depth limit may or may not help much.

[MikhailArkhipov]

Probably not very pressing at the moment after all the major work. Removing from epic, but leaving open for consideration.

[MikhailArkhipov]

Closing in favor of #472