NancyFx/Nancy — pull request #1456 by khellang (2014-02-13 18:14:31+00:00)
Title: Added more explanatory exceptions for bootstrapper locator and web.config section

This PR does the following:
- [x] Added exceptions to `NancyHttpRequestHandler` for four scenarios
- The bootstrapper specified in web.config is not found
- The bootstrapper specified in web.config does not have a default ctor, or the default ctor throws.
- The `type` attribute of the bootstrapper element in web.config is empty
- The `assembly` attribute of the bootstrapper element in web.config is empty
- [x] Added exceptions to `NancyBootstrapperLocatorFixture` for two scenarios
- Multiple bootstrapper types are found (since we don't know which to pick, we might as well force the user to do it).
- The located bootstrapper does not have a default ctor, or the default ctor throws.

I reused the `BootstrapperException` for all scenarios.

This should provide users with better, more explanatory messages when bootstrapper location/initialization fails :sparkles: