Improve generator error message (#1089)

* add additional information to TestGenerationError

* handle exceptions

* sort loaded assemblies

Update changelog.txt

use build source dir env variable

add tests for Feature/Scenario Hooks with context parameters (#925)

Update for 2.2 release

update changelog for 2.2.0-prerelease20170523

update TestGenerator version

Update changelog and format release date in ISO8601

update changelog.txt

add bin and pdb to build artifacts