Update In Place

This pull requests represents the update-in-place functionality. 

Components that were added:

Signature file support:
We now download a signature file at the same time that we download the update installer. This signature file is used to validate the installer using a public key.

DynamoCrypto Library:
Methods for finding certificates in certificate stores, extraction of public or private keys, and verification of installers. A certificate containing our public key (Dynamo.cer) is now in the DynamoCrypto directory and is placed in the main build directory. When the user first installs an update, this certificate will be registered in their "current user" certificate store.

InstallDynamo console application: 
Uses DynamoCrypto methods to verify an installer against a signature file using public key before beginning install.

SignDynamo console application:
Uses DynamoCrypto methods to generate a signature file for Dynamo based on a private key. In order to test this functionality you must install the private key on your machine, or test through the CI (where the private key has been installed). The signature file is placed in the same directory as the installer and is uploaded to S3.

@lukechurch Please review.