Snippets: Fill constructor shortcut with class name and move cursor to parameters

## Environment data

`dotnet --info` output:
.NET Command Line Tools (1.0.0-preview2-003121)

Product Information:
Version: 1.0.0-preview2-003121
Commit SHA-1 hash: 1e9d529bc5

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.11
OS Platform: Darwin
RID: osx.10.11-x64
VS Code version: 1.4.1
C# Extension version: 1.3.0
## Steps to reproduce
- Create a new class
- type the shortcut for constructor: ctor
## Expected behavior
- I should have the class name in the constructor and should not have to tab to give the class name then tab again to go to the Parameters section which IMO should be blank
## Actual behavior
- I have the following code generated:
`public ClassName(Parameters)`