New MUE wallet release V2.1.2

This is a non-mandatory update, but includes several improvements over previous v2 versions

Including in this new client;

Added proposal voting tab.
Fix transaction display times.
Fixed compiler warning for class vs. struct.
Updated PNG and ICO files with MUE logo.
Updated checkpoint block, version, and gitian descriptors.
Added PPCoin copyright notices.
Updated README files.
Bug fix for checkpoints that was causing wallets and masternodes to get stuck while loading blocks.