Hook in Review Bot extension into the Review Board UI and adding a lightbox for manual trigger of Review Bot tools. Also includes new API resource for pulling down installed tools.

Tested the new API resource in Firefox to ensure the expected data is being pulled down.
Manually tested that the tools lightbox loads with the list of  all enabled tools that are also enabled to be run manually.
Ensured that the UI experience works as expected : correct buttons displayed for correct options, run button disabled if no tools are checked, appropriate text in light boxes per situation.