Refactor client and client-cli

Changed a few things. It's mostly organizational. Namely:

+ renamed 'Start' to 'Home'
+ reorganized client-cli into 'main.go' 'home.go' and 'genericwallet.go'
+ commented out functions that don't work / can't be used right now (anything relating to upload, download, send money, resize)
+ switched Keypair from pointer to non-pointer
`os.Getenv("HOME")` is the lazy way. A more cross-platform-friendly approach is:
```go
import "os/user"
homedir := user.Current().HomeDir
```