VisualStudio for ARM build

VS2017 now offers solution options for Android and iOS applications. It includes the GCC cross-compiler suite and property sheets for configuring a project for those platforms and libraries for cross-platform mobile application development.

The provided solution file will build wolfSSL for linking into an ARM based application, libwolfssl.a. The user_settings.h file enables some of the hardened settings and disables most uncommon ciphers.