Add tests

[DearRude]

• auth should be done in handleFtpServer instead of each file individually
• command functions return error
• make db interface instead of direct access
• make conn interface instead of direct access
• find a way to mock the ftpserver
• add respective tests for webserve. there are a few things listed in echo documentations.
• have unit tests for general program functionality
• add integration tests for db?