Add URL builder helper to HTTPClient
Improve UploadLog interface by separating returned URLs from errors
Add 'Analyze' menu entry and button where applicable to LogUploader UI

Also add separate analyzerURL field to LogUpload result
Extract non request specific parts from LogUploader HTTP helper
Add LogUploader helper to detect HTTP redirects

Also handles the non standard X-Gist-Url header sent by GitHub sometimes
Resolve full GitHub Gist URL for analyzer invocation