Add Height to Proof of Work Reward and Change

Add Height to Proof of Work Reward and Change to 5.2 at block 449000
Update Logos
Start POS Height and Disable Continuous POS
Change Min and Max POS Age

Change min and max pos age. POS is enabled at block 450000 to stop
forking early.
Start POS at Block 450,000
Update to display Pop up Wallet Backup
Update encrypt message
Update Checkpoints and Version
Update Coinstake
Updated Proof of Stake
Update main.cpp
Update version.h
Update Wallet Logo
Update checkpoints.cpp
Update checkpoints.cpp
Update checkpoints.cpp
Merge pull request #2 from dx11/dev

Update to POS