Add OnBeforeNavigation implementation (can be user implemented using IRequestHandler)
Implement OnBeforeBrowse
Remove OnBeforeNavigation it's in the current Cef build we're using, though looks like it will be deprecated shortly.
For now use OnBeforeBrowse
Update comments where possible (based on Cef3 Api doc)
OnBeforeResourceLoad - Set Url for Redirect
Merge pull request #354 from amaitland/feature/add-onbeforenavigation

Add OnBeforeBrowse method