Auto set the release stage

Set the release stage to dev if we are compiled with DEBUG on, or if the
debugger is attached - else default to production.
Set CI build on Release and Debug configurations
Uses CONFIGURATION environment variable to path to code analysis files
Fixed parameter grouping in CI config
Corrected unit tests based on build configurations
Removed #DEBUG Release stage set
Merge branch 'master' of https://github.com/CodeHex/Bugsnag-NET into release-stage-autoset

Conflicts:
	appveyor.yml
	src/Bugsnag.Core/Configuration.cs
Merge pull request #6 from CodeHex/release-stage-autoset

Auto set the release stage