Test get args raises exception with mutually inclusive args

get_args function from console interface should raise
exception when mutually inclusive groups are not passed
together. Those options are -c or --clipboard and -g
or --get
Test check_passaprase function from console interface
Add encrypt method to Database
Refactor tests
Redesign database add credential not to call encrypt
Update database encrypt tests
Refactor tests
Refactor tests. Tests runs now in less than one second
Add decrypt method to Database
Refactor console interface
Ignore test database files
Test get password function in console interface
Add gitkeep to tests database directory
Test list credential prints expected credential information
Refactor database gpg_key attribute to key
Fix setup database function
Refactor setup testing database method
Test prompt credential returns Credential instance
Test cli add credential to database
Test cli copy_to_clipboard function