Update version to 7.1 RTM
Encapsulate reusable components into XunitServiceProvider
Fix issue when run tests with the same structure in different projects,
for example projects which share code.
Refactoring of XunitTaskRunner
Add ReSharper v8 EAP plugin
Add R# v7 plugin
Add R# v6.1 plugin
Fixed copyright date
Remove version as we have universal installer.