Add tasks to dump/download application database

- mysql:dump:do generates the dump
- mysql:dump:get downloads the generated output
Use scp instead of sftp

- Use scp instead since it has less overhead
- Also don't need to specify destiny filename (uses same as source)
Add task to apply dump locally

- Searches 'dumps' folder and applies the last one generated to
  development database specified by 'config/database.yml'
- Also try to be consistent in command execution style
Properly exclude password from mysql arg list