Target netstandard 1.3

Update TargetFrameworkVersions.

Merge master into future

This reverts commit a96d7825.

This reverts commit ca967cfe.

Merge stabilization into master

invoke next handler in case if no signature help providers can be fou…

Added dependencies projects to other solutions

Merge remote-tracking branch 'upstream/stabilization' into merge-stabilization-into-master20160418-171725

Invoke next handler in case if no signature help providers can be fou…

Unified dependencies to xUnit

Remove System.AppContext to Roslyn.VisualStudio.InteractiveComponents

Update Solution.GetProject(IAssemblySymbol) [Fixes unit test flakiness]

Update FX dependencies to build 24011

Remove redundant instance of SpeculativeTCompletionProvider inside CSharpCompletionService

Merge master into future

invoke next handler in case if no signature help providers can be found (i.e. if document for the text snapshot cannot be found)

invoke next handler in case if no signature help providers can be found (i.e. if document for the text snapshot cannot be found)

Allow interactive window evaluation of empty line.

Fix DSR.PortablePdb package version

Reference as much of the VS SDK as we can via NuGet packages

Merge stabilization into master