Added my prior changes to Aaron's most recent branch.

Aaron,  I've created a new view controller for preferences.  Currently it allows you to indicate your denomination (BTC, mBTC, uBTC) as well as a bitcoin symbol.  This can be expanded to allow the user to select his exchange rate, etc.  I've also added a currently non-functional tableview section for developers.  I'd like the ability to switch between the mainnet and the testnet without compiling for development purposes.  This would be suppressed  in a release obviously.  Let me know what you think.