AppVeyor Automated Build Services for Windows Binaries

**User Story**
As a `Windows User` I want `trusted binaries` so that I may `deploy the BitShares software without building from source`.

Related Tasks:
* #958 Provide Automated Build Services to for macOS and Linux

**Task List**
- [ ] Define Test Cases
- [ ] functioning demo within personal repo
- [ ] Script for Core Team to GitHub and/or Travis-CI settings
* [x] Connect AppVayor to GitHub for the `bitshares-core` repo
* [ ] Build Configuration (https://www.appveyor.com/docs/build-configuration/)
* [ ] Build pipeline
* [ ] Configuring build
* [ ] Build versioning
* [ ] AssemblyInfo patching
* [ ] NET Core `.csproj` files patching
* [ ] Clone directory
* [ ] Environment variables
* [ ] Script blocks in build configuration
* [ ] Installing additional software
* [ ] Hosts entries
* [ ] Build matrix
* [ ] Rolling builds
* [ ] Scheduled builds
* [ ] Build Queue
* [ ] Testing
* [ ] Pull Request

**Additional Context (optional)**
* Currently the BitShares-Core Team provide binaries with each tagged release for both Windows and Linux. However, they could be produced in a more transparent way.
* The BitShares-UI Team uses AppVeyor for Windows binaries with each releases. This Issue intends to build upon their successes.
* AppVeyor (https://www.appveyor.com/)
* Build Environments (https://www.appveyor.com/docs/build-environment/):
* Visual Studio 2013
* Boost: 1.56, 1.58
* OpenSSL: OpenSSL 1.0.2L
* Visual Studio 2015
* Boost: 1.60, 1.62, 1.63, 1.65, 1.66, 1.67
* OpenSSL: OpenSSL 1.0.2L
* Visual Studio 2017
* Boost: 1.65, 1.66, 1.67
* OpenSSL: OpenSSL 1.0.2L

## CORE TEAM TASK LIST
- [x] Evaluate / Prioritize Feature Request
- [x] Refine User Stories / Requirements
- [x] Define Test Cases
- [ ] Design / Develop Solution
- [x] Assigned: @marcialvieira
- [x] Estimated: 10 hours
- [ ] Perform QA/Testing
- [ ] Update Documentation

Start with the AppVeyor build-configuration documentation and the existing GitHub connection for the bitshares-core repository. Define the Windows build pipeline, configuration, build matrix, testing, and binary output described in the task list; done means a transparent, functioning AppVeyor build producing trusted Windows binaries.

Written by the indexing model from the issue text.