Dependency Graph Filtering

### Current Behavior:
The Dependency Graph implementation is currently displays all dependencies (excepting #85) but lacks functionality that would aide using it as a tool.

### Proposed Behavior:
Add filtering so that one can cut through the noise of a 300 component maven project (or 1000 component npm project!).
* Filter by vulnerabilities. Thus, if (X depends on Y and Y depends on Z) and Z has a vulnerability, then seeing that on the graph might point one in the direction of first checking if an update is available for X.
* Filter by license policy violation... I want to know how a problem license is getting into the project
* Indicate when dependencies have scope "optional". A problem dependency that is optional can be excluded!
* Indicate on the tree when dependencies have updates available. In the XYZ example above, this might point one to updating Y is there is no update available for X, or Z itself (the vulnerable component) is no updates exist for X or Y.