Various Darksend Improvements

- Denomination label shows n/a after reset now
- Fixed collateral checking bug introduced by updating to Bitcoin v9 codebase
Implemented KeePass Integration

More info regarding KeePass: http://keepass.info/

KeePass integration will use KeePassHttp (https://github.com/pfn/keepasshttp/) to facilitate communications between the client and KeePass. KeePassHttp is a plugin for KeePass 2.x and provides a secure means of exposing KeePass entries via HTTP for clients to consume.

The implementation is dependent on the following:
- crypter.h for AES encryption helper functions.
- rpcprotocol.h for handling RPC communications. Could only be used partially however due some static values in the code.
- OpenSSL for base64 encoding. util.h libraries were not used for base64 encoding/decoding since they do not use secure allocation.
- JSON Spirit for reading / writing RPC communications

The following changes were made:
- Added CLI options in help
- Added RPC commands: keepass <genkey|init>
- Added keepass.h and keepass.cpp which hold the integration routines
- Modified rpcwallet.cpp to support RPC commands
Refactored encryption / decryption and base64 routines
Refactored KeePassHttp protocol implemenation