- API to get a value given a key
- API to update value smartly
- Fine grained configuration change event
- Smart reload API
- Remove unnecessary APIs

Use WorkspaceFolder instead of URIs in IWorkspaceContextService

Adopt to use getWorkspaceState instead of hasFolderWorkspace or hasMultiFolderWorkspace

This reverts commit 6dd25f08.

* Update definition of Promise in winjs.base.d.ts.

* Update to new Promise declaration

* Fix remaining errors.

- Revert auto saving settings
- Revert virtual editor for workspace settings in MR workspace

- Workspace context service
- Workspace configuration service
- Configuration editing service
- Workspace editing service