Improved console logging
Previously, when using console.log facilities, only the first argument was
respected by ConsoleHelper, resulting in information not being logged when
console.log was invoked with multiple arguments.
Additionally, arguments would be converted straight to strings, resulting
in [object Object] or similar results in the log.

This change allows any number of arguments to be passed to the logging
functions and it converts the inputs to a representation that is useful
when debugging the application.

A call like log( "a", 123, { foo: 'bar' }, function() { return 'baz'; } );
Results in: a,123,{"foo":"bar"},function () { return 'baz'; }
Use the newer AppDeployCmd when available
The old XapDeployCmd could raise "Error: The parameter is incorrect." with project files that were opened with more recent versions of Visual Studio.
This change looks for the Windows Phone SDK 8.1 AppDeployCmd before falling back to the WP SDK 8.0 XapDeployCmd.
Merge branch 'feature/console-helper'