Added possibility to read users and passwords from two separate files…

[mfulz]

…. Removed "-" arg as need to read from stdin

This PR will provide a possibility to use bruteforce reading users and passwords from two separate files.

It changes the args to work in the following way:

• no arg -> read from stdin (user:password)
• one arg -> read from combo file (user:password)
• two args -> read users from file (first arg) and passwords from file (second arg) line by line

It is iterating outer over passwords and users in the inner loop.

example:
Users "u1,u2"
Passwords "p1, p2, p3, p4"

will parse in the following order:
u1:p1
u2:p1
u1:p2
u2:p2
...