Added make_unique to Kryvos class.

Continued to add make_unique where it is missing, in Kryvos.cpp. Added
braces to initialize the Kryvos object in main.cpp.
Added C++11 syntax improvements

Added auto and initializer braces to Crypto.cpp.
Updated Botan library

Updated Botan library: built with GCC 4.8.2 SEH. Now buliding Kryvos
with Qt 5.3.1. Updated .pro file to match new Qt Creator file path
locations on Windows.
Switched to JSON for settings

Switched to using JSON over ini files. Now checking if stylesheet file
opens successfully before trying to read it.