Move Apache licence comment to end of .sln file

[brendancosmanmammoth]

Visual Studio 2012 and 2015 will not open a solution file that starts with multi line comments. (I was not able to test other Visual Studio version, but I suspect the behavior would be the same).

This change makes the solution file valid while retaining the licence information.

[brendancosmanmammoth]

Do not merge...

I'll leave this pull request open for comments, but I've identified a few other trivial changes that should be made (that I don't have time for today), including...

• the new project template solution file also is invalid due to the multi line comment (https://github.com/apache/usergrid-dotnet/blob/master/new-project-template/new-project-template.sln)
• the client attempts to connect to an endpoint that is no longer available (at least for sandbox / trial users) (https://github.com/apache/usergrid-dotnet/blob/master/Usergrid.Sdk/Client.cs#L27) - should be https://apibaas-trial.apigee.net for trials and I assume https://apibaas.apigee.net for production.