Dynamic analysis support

[nickdaugherty]

In addition to Scanner's static analysis, Scanner should support dynamic analysis of sites.

This would consist of finding site urls and crawling them, while recording what happens, such as expensive MySQL queries, PHP Warnings, etc.

Essentially, we'd need:

• An engine to do the actual crawling
• Somewhere to store results as they happen (CPT likely)
• Hooks on things we are interested in, such as queries, to record various states
• UI component to trigger
• Automatic, periodic scanning like we have for static analysis
• CLI command
• UI for results

[joshbetz]

:+1: